石家庄地区早全新世冷湿气候的牙齿微磨痕和同位素证据

早全新世11~8kaB.P.是末次盛冰期之后全球经历的第一个温暖期,研究表明该时期华北气候温暖湿润,但在8.2kaB.P.华北对全球冷事件的响应没有相关报道。本文通过~(14)C测年和冲刷事件对比手段确定石家庄河床沉积中的诺氏古菱齿象(Palaeoloxodon naumanni)-披毛犀(Coelodonta antiquitatis)动物群生活在8.2kaB.P.时期。对来源于石家庄市郊区砂砾石层中的5件成年古菱齿象牙釉质样品进行了XRD粉末衍射、碳氧同位素和牙齿微磨痕分析。结果表明,牙齿XRD粉末衍射模式与现生大象相似,说明未受到地下水的影响;碳同位素分析表明早全新世华北东部为森林草原环境;极低的氧同位素值说明当时气候寒冷或湿润,地层中的针叶林茎杆和披毛犀化石也说明气候的寒冷;石家庄地区古菱齿象的凹坑痕出现频率极低,长条痕缺乏纤细类型。这种模式说明石家庄地区的古菱齿象以木质茎秆(55%)和草(45%)为食,而湿润季节以草为食是大象的特点,当时的石家庄是气候寒冷或湿润的针叶林草原环境。     

水系沉积物找金的冷冻采样法

众所周知,在金矿勘查中。采集和分析具有代表性的水系沉积物样品是个难题。本文介绍了一种从活动的水系沉积物中采集原状、封闭样品的冷冻采样法,并对苏格兰科诺尼什境内的一条流经金矿区的河流进行采样试验,以此对该法进行评价。 常规采样法的缺点在于粉金因淘洗有不同程度的损失。冷冻采样法则可获得具有代表性和定量性的数据。若能与砾石层河流沉积学方面的资料相结合,还可建立探测矿源的矿质分散模式。这表明,冷冻采样法特别适用于大型金矿勘测中的定位阶段。     

东秦岭造山带花岗岩类长石铅同位素组成及其构造学意义

本文对东秦岭造山带内２７个花岗岩类央体４８件长石样品进行了铅同位素成分的测定，结果表明，本区的南秦岭不同时代花岗岩类以贫铀铅和钍铅为特征，具有明显的铅同位素块体效应，反映它们属地同一个铅同位素构造－地球化学省；而本区的北秦岭区岗岩类从晚元古代到早古生长，长石铅同位素组成以富铀铅和钍铅的为特征，但从晚古生长开始，花岗岩类长石铅同位素组成明显发生变化，以贫铀铅和钍铅为特征，反映晚古生长及其后形成花岗质     

地下水采样技术及《地下水采样技术规程》的编制

地下水取样是地下水调查、监测中的一项关键技术工作,必须要根据调查场地的条件和调查的目的选择合适的采样方法,并严格按照操作规程进行采样,以取得真实、有代表性的样品。本文在梳理常用地下水采样方法和采样器具的基础上,介绍了行业标准《地下水采样技术规程》的编制过程及其主要内容。该规程内容涉及地下水现场测试样品、无机检测样品、有机检测样品、气体检测样品、同位素检测样品、专项样品（包括地热水样品和饮用矿泉水样品）等的采集要求、采样方法、样品保存、质量控制等。     

金刚石指示矿物找矿采样技术

指示矿物和指示元素可提供金刚石矿源存在的直接证据，在金刚石原矿勘查中应用广泛。确定靶区前，对所有找矿线索和金刚石找矿标志都要检测，并进行系统的追索。金刚石勘查中使用最成功和应用最广泛的勘查方法是重矿物采样法，主要搜集指示矿物和金刚石。世界上许多金刚石矿床都是利用这种方法发现的。本文着重探讨重矿物采样的关键技术问题，包括样品选择、样品的大小与重量、采样间距和样品的处理与加工。水系采样要特别注意样品的选择和评价。地球化学和动植物勘探方法在金刚石勘查中受到多种因素制约，本文也对其进行了探讨。指示元素采样设计和实施的每个阶段、样品分析和成果解释都要认认真真、周到细致的落实。各阶段的效果直接关系着其找矿效果，对决定是否实施项目进一步勘探也至关重要。     

利用湖泊自生碳酸盐岩氧碳同位素特征分析古湖泊类型的方法——实际应用中的要点及分析程式

以文献资料为素材,讨论了湖泊自生碳酸盐岩样品构成中岩性成分、采样点分布及数据量对样品氧碳同位素相关性及其能否反映古湖泊氧碳同位素相关性影响,指出根据相关性分析古湖泊类型时,必须充分考察样品岩性成分一致性、地质层位同一性、地质及地理分布合理性,着重考察样品数据量的充足性.综述了利用湖泊自生碳酸盐岩氧碳同位素特征分析古湖泊类型的方法,提出"一氧、二碳、三相关、四综合"的基本分析程式.     

二次离子质谱微区原位牙形石氧同位素分析及其在古海表水温记录中的应用

利用生物成因磷灰石的氧同位素信息能够重建古海水温度,尤其是牙形石,结合其在生物地层学上的研究,它的数据解释具有明确的古环境意义。牙形石微小的个体一直是其精确地球化学分析的限制因素。作为对牙形石微区原位氧同位素测试方法的探索研究,本文利用Cameca IMS--1280 型二次离子质谱仪对牙形石进行了微区原位氧同位素组成测试,通过分析得到可靠的古表层海水温度 ( SST) 记录,表明从晚二叠世到早三叠世SST 存在明显的上升过程。相比常规Ag3PO4 实验方法,牙形石微区原位氧同位素分析方法更加快速,而且能够有效避免牙形石易受到污染的部位,获得更为可靠的牙形石氧同位素组成的测定结果。     

贾湖史前人类迁移行为的初步研究——锶同位素分析技术在考古学中的运用

位于河南省舞阳县的贾湖遗址是一处著名的新石器时代遗址,距今7800～9000年。遗址中出土了大量的人和动物的骨骼与牙齿,这为研究史前时期中国中部地区人类的迁移情况提供了很好的材料。在本次研究中,共分析了26个人和动物样品,包括12个人体骨密质样品、9个人牙釉质样品和5个猪牙釉质样品。测定了每个样品的锶同位素浓度和87Sr/86Sr比值,结果表明猪牙釉质的锶同位素浓度（平均值为196±51ppm,n=5,1σ）高于人牙釉质的浓度（平均值为110±61ppm,n=9,1σ）,人骨骼的锶同位素浓度（平均值为444±173ppm,n=12,1σ）明显地高于人牙釉质的浓度。根据5个猪牙釉质样品87Sr/86Sr平均值±2倍的标准偏差确定的当地锶同位素比值范围（0.712205～0.712420）,发现14个人类个体中有5个是外来迁入的,并且从第1期到第3期人口的迁移率有增加的趋势。这是在国内首次利用锶位素分析方法对古人类的迁移现象进行研究,同时也表明此方法可以很好地判断古人类迁移行为。     

古盐度复原法综述

古盐度的复原是恢复古环境、认识环境变化过程与机理的一种重要方法。其中包括适用于半咸水环境的沉积磷酸盐法 ,目前应用广泛的同位素法 (主要是氧同位素法和碳同位素法 )。微量元素法也是一种重要的古盐度复原法 ,其依据采样环境不同可分为硼元素法 (适用于粘土性矿物 )和Sr/Ca法 (常用于对湖泊沉积物进行分析 )等。由于古环境是一个开放体系 ,因此不可避免地要受到外界环境的干扰 ,为了使古盐度复原更加接近实际 ,上述方法应该综合使用。     

基岩区寻找隐伏矿的地球化学方法:构造地球化学测量

构造地球化学测量是在基岩出露区发现深部矿化信息的一种较为有效的方法。本文介绍了构造地球化学的一些基本概念和构造地球化学测量方法的发展历程。为解决岩石样(构造岩样)的代表性和均匀性,提出了方格采样法,即在每个采样网格内多点采样组合分析采样方法,采集以构造破碎带物质、裂隙充填物、蚀变岩石、矿化岩石等为主的能反映深部矿化信息的样品。利用该方法在甘肃西和地区进行了1∶50 000构造地球化学测量试验,采用500 m×500 m的采样网格,在每个采样单元中采集6~8个子样组合,分析了其中的Au、Ag、Pb、Zn等19种元素,圈定了较好的金地球化学异常,经查证发现了金矿体。在江西岩背锡矿外围开展1∶10 000的构造地球化学测量试验,采用100 m×100 m的网格,采集构造裂隙样品,圈定了Sn等元素的地球化学异常,对圈定的Sn地球化学异常进行钻探验证,发现深部隐伏Sn矿体。不同比例尺的构造地球化学测量试验表明,构造地球化学测量在基岩出露区能有效发现深部矿化信息,在寻找隐伏矿工作中具有较好的应用前景,在中国黔西南地区寻找卡林型金矿和东南沿海地区火山岩覆盖区找矿中能发挥一定的作用。     

Mammoth tooth enamel growth rates inferred from stable isotope analysis and histology

Mammoth (Mammuthus sp.) teeth are relatively abundant in Quaternary deposits from Eurasia and North America, and their isotopic compositions can be used to reconstruct past seasonal patterns in precipitation, diet, and migration. Strategies for collecting and interpreting such data, however, are strongly dependent on growth rates, which can vary among species, individuals, and within teeth. In this study, we use histological and isotopic measurements to determine enamel growth rates for a Columbian mammoth (Mammuthus columbi) tooth in two directions. Using histology, the growth rate through the enamel thickness (ET; perpendicular to the height of the tooth) is estimated at 0.8 to 1.5 mm/yr. Isotopic sampling through the innermost 0.36 mm of the ET recovered less than half a period of variation (i.e., half an inferred year of growth), which is consistent with the histological estimate for ET growth rate. A combination of histological and isotopic measurements suggests that the enamel extension rate (growth in the height of the tooth) is 13–14 mm/yr. Knowledge of enamel growth rates should improve the design and interpretation of future isotopic studies of mammoth teeth. The combination of histological and isotopic measurements may also prove useful in determining growth rates for other extinct taxa.     

Seasonal variation in kangaroo tooth enamel oxygen and carbon isotopes in southern Australia

Serial sampling of tooth enamel growth increments for carbon and oxygen isotopic analyses of Macropus (kangaroo) teeth was performed to assess the potential for reconstructing paleoseasonality. The carbon isotope composition of tooth enamel apatite carbonate reflects the proportional intake of C₃ and C₄ vegetation. The oxygen isotopic composition of enamel reflects that of ingested and metabolic water. Tooth enamel forms sequentially from the tip of the crown to the base, so dietary and environmental changes during the tooth's formation can be detected. δ¹³C and δ¹⁸O values were determined for a series of enamel samples drilled from the 3rd and 4th molars of kangaroos that were collected along a 900 km north–south transect in southern Australia. The serial sampling method did not yield pronounced seasonal isotopic variation patterns in Macropus enamel. The full extent of dietary isotopic variation may be obscured by attenuation of the isotopic signal during enamel mineralisation. Brachydont (low-crowned) Macropus teeth may be less sensitive to seasonal variation in isotopic composition due to time-averaging during mineralisation. However, geographic variations observed suggest that there may be potential for tracking latitudinal shifts in vegetation zones and seasonal environmental patterns in response to climate change.     

Inverse methods for estimating primary input signals from time-averaged isotope profiles

Mammalian teeth are invaluable archives of ancient seasonality because they record along their growth axes an isotopic record of temporal change in environment, plant diet, and animal behavior. A major problem with the intra-tooth method is that intra-tooth isotope profiles can be extremely time-averaged compared to the actual pattern of isotopic variation experienced by the animal during tooth formation. This time-averaging is a result of the temporal and spatial characteristics of amelogenesis (tooth enamel formation), and also results from laboratory sampling. This paper develops and evaluates an inverse method for reconstructing original input signals from time-averaged intra-tooth isotope profiles. The method requires that the temporal and spatial patterns of amelogenesis are known for the specific tooth and uses a minimum length solution of the linear system Am = d, where d is the measured isotopic profile, A is a matrix describing temporal and spatial averaging during amelogenesis and sampling, and m is the input vector that is sought. Accuracy is dependent on several factors, including the total measurement error and the isotopic structure of the measured profile. The method is shown to accurately reconstruct known input signals for synthetic tooth enamel profiles and the known input signal for a rabbit that underwent controlled dietary changes. Application to carbon isotope profiles of modern hippopotamus canines reveals detailed dietary histories that are not apparent from the measured data alone. Inverse methods show promise as an effective means of dealing with the time-averaging problem in studies of intra-tooth isotopic variation.     

The isotope record of short- and long-term dietary changes in sheep tooth enamel: Implications for quantitative reconstruction of paleodiets

Quantitative reconstruction of paleodiet by means of sequential sampling and carbon isotope analysis in hypsodont tooth enamel requires a precise knowledge of the isotopic enrichment between dietary carbon and carbon from enamel apatite (ε_D-E), as well as of the timing and duration of the enamel mineralization process (amelogenesis). To better constrain these parameters, we performed a series of controlled feeding experiments on sheep ranging in age from 6 to 24 months-old. Twenty-eight lambs and 14 ewes were fed isotopically distinct diets for different periods of time, and then slaughtered, allowing the timing and rate of molar growth to be determined. High resolution sampling and stable carbon isotope analysis of breath CO₂ performed on six individuals following a diet-switch showed that 70-90% of dietary carbon had turned over in less than 24 h. Sequential sampling and carbon isotopic analysis was performed on the first (M₁) and second (M₂) lower molars of four lambs as well as on the third lower molar (M₃) of 11 ewes. The changes in diet were recorded in all molars. We found that the length of enamel matrix apposition is approximately one-quarter of the final tooth length during crown extension, and that enamel maturation spans slightly less than 3 months in M₁, and 4 months in M₂ and M₃. Portions of enamel in equilibrium with dietary carbon were used to calculate ε_D-E values. Animals on grass silage diets had values similar to previous observations, whereas animal switched to pelleted corn diets had values ca. 4‰ lower, a pattern consistent with lower methane production observed for animals fed concentrate diets. The tooth enamel forward model of Passey and Cerling (2002) closely predicted the amplitude of isotope changes recorded in tooth enamel, but slightly underestimated the rate of isotope change, suggesting that the rate of accumulation of carbonate during maturation may not be constant over time. Although stable isotope profiles in tooth enamel represent underdetermined systems, our results demonstrate that they can provide useful information about dietary variability if the mineralization process is taken into account.     

Tooth enamel mineralization in ungulates: implications for recovering a primary isotopic time-series

Temporal changes in the carbon and oxygen isotopic composition of an animal are an environmental and behavioral input signal that is recorded into the enamel of developing teeth. In this paper, we evaluate changes in phosphorus content and density along the axial lengths of three developing ungulate teeth to illustrate the protracted nature of mineral accumulation in a volume of developing enamel. The least mature enamel in these teeth contains by volume about 25% of the mineral mass of mature enamel, and the remaining 75% of the mineral accumulates during maturation. Using data from one of these teeth (a Hippopotamus amphibius canine), we develop a model for teeth growing at constant rate that describes how an input signal is recorded into tooth enamel. The model accounts for both the temporal and spatial patterns of amelogenesis (enamel formation) and the sampling geometry. The model shows that input signal attenuation occurs as a result of time-averaging during amelogenesis when the maturation interval is long compared to the duration of features in the input signal. Sampling does not induce significant attenuation, provided that the sampling interval is several times shorter than the maturation interval. We present a detailed δ¹³C and δ¹⁸O record for the H. amphibius canine and suggest possible input isotope signals that may have given rise to the measured isotope signal.     

Sources of carbon isotope variation in kangaroo bone collagen and tooth enamel

The stable carbon isotopic composition (expressed as δ¹³C) of herbivore remains is commonly used to reconstruct past changes in the relative abundance of C₄ versus C₃ grass biomass (C₄ relative abundance). However, the strength of the relationship between herbivore δ¹³C and C₄ relative abundance in extant ecosystems has not been thoroughly examined. We determined sources of variation in δ¹³C of bone collagen and tooth enamel of kangaroos (Macropus spp.) collected throughout Australia by measuring δ¹³C of bone collagen (779 individuals) and tooth enamel (694 individuals). An index of seasonal water availability, i.e. the distribution of rainfall in the C₄ versus C₃ growing seasons, was used as a proxy for C₄ relative abundance, and this variable explained a large proportion of the variation in both collagen δ¹³C (68%) and enamel δ¹³C (68%). These figures increased to 78% and 77%, respectively, when differences between kangaroo species were accounted for. Vegetation characteristics, such as woodiness and the presence of an open forest canopy, had no effect on collagen or enamel δ¹³C. While there was no relationship between collagen δ¹³C and kangaroo age at death, tooth enamel produced later in life, following weaning, was enriched in ¹³C by 3.5‰ relative to enamel produced prior to weaning. From the observed relationships between seasonal water availability and collagen and enamel δ¹³C, enrichment factors (ε^∗) for collagen-diet and enamel-diet (post-weaning) were estimated to be 5.2‰ ± 0.5 (95% CI) and 11.7‰ ± 0.6 (95% CI), respectively. The findings of this study confirm that at a continental scale, collagen and enamel δ¹³C of a group of large herbivores closely reflect C₄ relative abundance. This validates a fundamental assumption underpinning the use of isotopic analysis of herbivore remains to reconstruct changes in C₄ relative abundance.     

Analysis of coupled Sr/Ca and Sr/Sr variations in enamel using laser-ablation tandem quadrupole-multicollector ICPMS

We present in this study results obtained with a laser-ablation coupled with both a quadrupole and a multi-collector ICPMS. The simultaneous in situ Sr/Ca and ⁸⁷Sr/⁸⁶Sr measurements along growth profiles in enamel allows the concomitant diet and migration patterns in mammals to be reconstructed. Aliquots of the powdered international standard NIST “SRM1400 Bone Ash” with certified Sr and Ca contents, was sintered at high pressure and temperature and was adopted as the reference material for external reproducibility and calibration of the results. A total of 145 coupled elemental and isotopic measurements of herbivores enamel from the Kruger National Park, South Africa, gives intra-tooth Sr/Ca and ⁸⁷Sr/⁸⁶Sr variations that are well larger than external reproducibility. Sr/Ca profiles systematically decrease from the dentine-enamel junction to the outer enamel whereas ⁸⁷Sr/⁸⁶Sr profiles exhibit variable patterns. Using a simple geometric model of hypsodont teeth growth, we demonstrate that a continuous recording of the ⁸⁷Sr/⁸⁶Sr variations can be reconstructed in the tooth length axis. This suggests that the mobility of a mammal can be reconstructed over a period of more than a year with a resolution of a ten of days, by sampling enamel along growth profiles. Our geometric model of hypsodont teeth growth predicts that an optimal distance between two successive profiles is equal to the enamel thickness. However, this model does not apply to the Sr/Ca signal which is likely to be altered during the enamel maturation stage due to differential maturation processes along enamel thickness. Here, the observed constant decreases of the Sr/Ca ratios in the ungulates of Kruger National Park suggests that they did not changed of diet, while some of them were migrating.     

有机碳和有机分子碳同位素的地球化学意义

有机碳和有机分子碳同位素组成的研究不仅在沉积地层对比，油－油，油－源对比研究方向发挥了独特作用，而且在古气候，古环境研究方面更具有广阔的应用剪影。开展对全球气候变化及全球碳循环有重要意义的有机碳碳同位素组成及分布研究和对生物演化，恢复古生态，古环境有重要意义的化石及沉积物中有机分子的碳同位素成及分布研究已势在必行。     

青海共和盆地猛犸象化石的发现及意义

在青海共和盆地晚更新世河湖相沉积地层中发现了象类化石,对化石的基本特征进行了描述,依据牙片的釉质层、齿脊频率等特征初步鉴定为猛犸象类化石,并在同一层位发现了钙化树木化石.结合区域地质以及产出猛犸象属化石地层的沉积学特征、孢粉组合等的简要分析认为,共和盆地晚更新世晚期为干燥寒冷的气候环境.这一发现有助于认识中国猛犸象属动物的迁徙过程,以及青藏高原晚更新世的生物演化、气候变化和构造活动.同时,也为研究青藏高原第四纪以来生物进化、湖泊与河流演化、气候变化、古地理与古环境变迁等提供了新资料.