987 resultados para Colby dating


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Based on chronological and climatologic analysis of many young stalagmites in Shihua Cave at Beijing and Water Cave in Benxi, Liaoning Province, this dissertation aims to discuss some key points on quantitative reconstruction of high resolution climate change from micro bands time series in young stalagmites. On chronological aspect of micro bands time series in young stalagmite, the uppermost micro bands were testified formed in the sampling year or the year before sampling from long term and in situ experiment in Shihua Cave at Beijing. Have been observed detailed under microscope, the micro bands were counted and compared with high resolution TIMS-230Th or ICP-MS U series dating, the results show that the micro bands are annual bands. The microscopic characteristics of annual bands in North China is as follows after studying lots of young stalagmites: the interface appears to be carved, and there is a light line adjacent to it, which moves back and forth slightly when adjusting the microscope slide. The cross dating of annual bands from different stalagmites is experimented in this thesis. On climatologically aspect of micro bands times series in young stalagmites, one significant problem is that the deposition trend resulting from the variation of the stalagmite shape. Various deposition trends have been discussed and corrected before climatologically analysis of micro bands series. And the whole year in situ observation and analysis of dripping water in Shihua Cave provide us new evidence for climate information reserved in stalagmites micro bands. The stalagmites in the same cave may contain different climate information due to the micro hydrological condition. The annual bands of young stalagmites collected from North China can be used to reconstruct past climate changes quantitatively. The warm season temperature (May, June, July, August) is reconstructed using two annual bands time series from Shihua Cave, Beijing, which corresponds to the warm/cool periods very well in Chinese history documents. The precipitation record of past 500 years is reconstructed using two stalagmite annual bands series from Shihua Cave, which is consistent to the dryness/wetness records derived from historical documents too.

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Study on the structural coupling relationship between basin and range is not only helpful to recognize the basin formation and evolution systematically, but also to guide petroleum exploration in the basin. As a late Paleozoic Orogen, the South Tianshan Mountains reactivated and uplifted rapidly during the Cenozoic, and led to the Mesozoic-Cenozoic considerable thick deposits in the Kuqa Depression. The researches of the dissertation were carried out in the Kuqa depression-South Tianshan M ountain s ystem, a nd t he b rittle m icrotectonics w. ere c hosen as t he m ost important object. Based on observations and measurements of the field, we made detailed investigations on the geometry and kinematics of this area, and analyzed the abutting and cutting relationships and relative sequence of many brittle structures, such as joint, shear fractures, faults and some small-scale structures related to them closely. According to those brittle fractures' relationships with stress, the nature and variation of regional palaeostress field during the Cenozoic were studied through inversion of fault slip data and inferring stress state from joint sequences. And the deformation time was estimated primarily via ESR dating of faulting. Results show that the stress field varies as well in times as in space. The maximal principal stress direction shifted from the vertical to the horizontal, and stress regime from weak extension to strong compression from the Paleogene to the Neogene regionally. During the late Neogene, the structural deformation of the South Tianshan and the basin-range boundary was dominated by near N-S extension, while near N-S compressive deformation in the interior of the Kuqa Depression. There exits obvious differential stress state from the north to the south. ESR dating of the faulting during the Cenozoic indicates that, the normal faulting in the north edge of the Kuqa Depression have been active all along from the Miocene to the early Pleistocene, but the thrusting and reverse faulting in the interior only been active from the Pliocene to the early Pleistocene. On the base of those geological data and some geophysical information and theoretical calculation results, we infer that, the different stress regime the basin-range system is ascribed to the vertical uplift of the Tianshan Mountain. It was the vertical uplift that lead to the gravity-driven gliding of thick layers lying on the faulted basement from the South Tianshan Mountain to the Kuqa depression, and to folding and thrusting in the interior and frontal of the Kuqa depression. Combining the structural evolution with petroleum geological conditions of the Kuqa Depression, we think that the strong compressive deformation of the Kuqa Depression during rapid uplifting of the Tianshan Mountains from the Pliocene to the early Pleistocene play crucial role in the structural trap formation and proliferous gas accumulation.

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About 214 trees in 9 sampling sites, representing 5 endemic conifer species, were collected from the western Sichuan Province and eastern Qinghai Province, China. In this study, structure we try to investigate tree-ring sensitivity to climate in order to obtain primary information of reconstructing past climate from the trees in this region. All the 5 species present distinct ring boundaries ^ few ABS(absent rings) and available for cross-dating,which are all past the test by program COFECHA. Statistics for all the 8 tree-ring width residual chronologies present significant inter-correlation between series and high values of mean sensitivity. As well as the maximum latewood density of Picea crassifolia Kom and Pinus densata Mast. These results indicate usefulness of these chronologies for dendrochronological studies. Pearson correlation analyses were applied to provide a basic estimate of the causal relationships between tree-ring width and climate factors. We found some significant relationships between tree-ring width> maximum density and temperature as well as precipitation. Especially, there is high correlation between the maximum density of the Picea crassifolia Kom and the index of moisture, the ratio of precipitation and temperature, which can indicate well the climate; however the higher correlation can be see between the maximum density of Pinus densata Mast and the total temperature from June to September. Regardless of tree species, chronologies in our study region presented accordant variations of which may reveal strong common climate signal. Thus these chronologies are shown to be dependable for building tree-ring network in the nearly future. However, there are limitations in this study, only monthly mean of temperature and precipitation were available. Also, for this typical subtropical mountain system, meteorological stations are usually located in valley and biased to represent moisture conditions on the slopes. Thus the estimation of precipitation both in temporal and spatial domain was rather restricted. Further study, such as wood anatomy, physiology and densitometry, are needed for better understanding the environmental and climatic history in this area.

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Landslides are widely distributed along the main stream banks of the Three Gorges Reservoir area. Especially with the acceleration of the human economic activities in the recent 30 years, the occurrence of landslide hazards in the local area trends to be more serious. Because of the special geological, topographic and climatic conditions of the Three Gorges areas, many Paleo-landslides are found along the gentle slope terrain of the population relocation sites. Under the natural condition, the Paleo-landslides usually keep stable. The Paleo-landslides might revive while they are influenced under the strong rainfall, water storage and migration engineering disturbance. Therefore, the prediction and prevention of landslide hazards have become the important problem involving with the safety of migration engineering of the Three Gorges Reservoir area.The past research on the landslides of the Three Gorges area is mainly concentrated on the stability analysis of individual landslide, and importance was little attached to the knowledge on the geological environment background of the formation of regional landslides. So, the relationship between distribution and evolution of landslides and globe dynamic processes was very scarce in the past research. With further study, it becomes difficult to explain the reasons for the magnitude and frequency of major geological hazards in terms of single endogenic or exogenic processes. It is possible to resolve the causes of major landslides in the Three Gorges area through the systematic research of regional tectonics and river evolution history.In present paper, based on the view of coupling of earth's endogenic and exogenic processes, the author researches the temporal and spacial distribution and formation evolution of major landslides(Volume^lOOX 104m3) in the Three Gorges Reservoir area through integration of first-hand sources statistics, .geological evolution history, isotope dating and numerical simulation method etc. And considering the main formation factors of landslides (topography, geology and rainfall condition), the author discusses the occurrence probability and prediction model of rainfall induced landslides.The distribution and magnitude of Paleo-landslides in the Three Gorges area is mainly controlled by lithology, geological structure, bank slope shape and geostress field etc. The major Paleo-landslides are concentrated on the periods 2.7-15.0 X 104aB.R, which conrresponds to the warm and wettest Paleoclimate stages. In the same time, the Three Gorges area experiences with the quickest crust uplift phase since 15.0X 104aB.P. It is indicated that the dynamic factor of polyphase major Paleo-landslides is the coupling processes of neotectonic movement and Quaternary climate changes. Based on the numerical simulation results of the formation evolution of Baota landslide, the quick crust uplift makes the deep river incision and the geostress relief causes the rock body of banks flexible. Under the strong rainfall condition, the pore-water pressure resulted from rain penetration and high flood level can have the shear strength of weak structural plane decrease to a great degree. Therefore, the bank slope is easy to slide at the slope bottom where shear stress concentrates. Finally, it forms the composite draught-traction type landslide of dip stratified rocks.The susceptibility idea for the rainfall induced landslide is put forward in this paper and the degree of susceptibility is graded in terms of the topography and geological conditions of landslides. Base on the integration with geological environment factors and rainfall condition, the author gives a new probabilistic prediction model for rainfall induced landslides. As an example from Chongqing City of the Three Gorges area, selecting the 5 factors of topography, lithology combination, slope shape, rock structure and hydrogeology and 21 kinds of status as prediction variables, the susceptibility zonation is carried out by information methods. The prediction criterion of landslides is established by two factors: the maximum 24 hour rainfall and the antecedent effective precipitation of 15 days. The new prediction model is possible to actualize the real-time regional landslide prediction and improve accuracy of landslide forecast.

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我国西南地区分布有广阔的亚热带潮湿区岩溶,以贵州为中心,总面积达50万km2,是世界上连片分布面积最大的岩溶区。贵州高原地处青藏高原东南缘,云贵高原的东翼,是中国大陆“西高东低”地貌格局中重要的过渡区段,对其新生代地质、地貌演化进行研究无疑具有重要的意义,不仅是对贵州薄弱的新生代地质、地貌研究的补充,而且可以直接通过夷平面展开与青藏高原的对比,探讨青藏高原隆升对贵州高原的直接影响。风化壳作为夷平面的组成部分,在过去没有引起足够的重视,但随着成功实例的不断出现,人们逐渐开始认识到风化壳是夷平面识别和重建的重要依据,也是夷平面环境信息的重要载体。贵州作为碳酸盐岩集中分布区,碳酸盐岩风化壳剖面广泛存在,尤其在黔中、黔北等地区各级夷平面上均发育有红色风化壳,利用碳酸盐岩红色风化壳能为夷平面的识别和形成时代的确立提供可靠的证据,特别是风化壳形成年龄的确定对夷平面时标的建立更具有积极意义。有关贵州地区红色风化壳形成时代的确定,多年来已有一些学者对此展开了研究,但贵州红色风化壳形成时代的确定存在着很大争论。虽然存在其它原因的可能性,但造成这种争论的根本原因在于贵州红色风化壳形成时代是依据其它资料(如夷平面、气候事件等)推断出来的,而不是根据直接测年数据界定的。因此,风化壳直接测年才是解决问题的关键。 本文在前人工作研究的基础之上,利用扫描电镜手段对贵州碳酸盐岩地区上覆风化壳土层中的石英颗粒进行观察、统计、分析,为风化壳成土的物质来源寻找新的证据;同时,经地球化学分析、测试等手段,判断风化壳土层中的晶体石英颗粒为风化壳形成初期的新生矿物——次生石英颗粒,并利用裂变径迹测年法对这种次生石英颗粒进行测年,最终探讨贵州碳酸盐岩地区上覆风化壳土层的形成年代。主要取得了以下几点认识: 一、石英颗粒蚀刻条件的优选 由于石英颗粒裂变径迹的长度和数量与晶格、铀含量、年龄等因素有关,所以不同地区的石英颗粒样品的裂变径迹蚀刻条件也存在差别;目前国际上有关石英颗粒的裂变径迹测年应用的实例较少,还没有统一的有关石英颗粒蚀刻条件的国际标准;现有的石英颗粒蚀刻条件有多种,但是缺乏对这些方法的优缺点进行对比评价。因此,我们要进行反复的条件实验,对比不同石英蚀刻剂的蚀刻效率,找寻适合石英颗粒的最佳蚀刻剂。实验结果表明,40%的HF溶液为最佳蚀刻剂,最佳蚀刻时间:温度在4℃左右(冬季)时为40min;温度在29℃左右(夏季)时为30min。 二、石英的外形、表面机械作用特征及其指示意义 我们利用扫描电镜对石英颗粒外形特征进行观察、统计、分析,结果表明本次研究的石英颗粒形态类型主要有两种:棱状-次棱状石英颗粒以及圆状、次圆状石英颗粒,其中棱状-次棱状石英颗粒包含了一部分晶体形态较为完整的石英颗粒。 根据石英颗粒表面机械作用特征分析结果,结合剖面区域地质特征,可初步判断剖面中的石英颗粒有三种物质来源:碳酸盐岩中的原生碎屑石英,有长时间长距离搬运特征;燧石团块石英,有短距离搬运或原位沉积特征;晶形较完整的次生石英,无搬运特征。三种石英均具有原位特征,前两种类型的石英是直接对基岩的继承,第三种类型的石英是风化壳剖面的次生矿物。 三、石英颗粒表面的化学作用特征及其风化强度指示意义 我们通过对石英颗粒表面化学作用形态的观察,发现大兴剖面、新蒲剖面和官坝剖面的石英颗粒表面化学溶解作用和化学沉淀作用都非常强烈,这表明三个剖面均处于湿、热环境中,均处于强烈的化学风化阶段。而且大兴剖面中石英颗粒表面的化学作用最强烈,气候较其他两个剖面更湿热,剖面的风化强度也最大,即各剖面的风化强度由强到弱排序为:大兴、新蒲、官坝。这一结果与矿物组成分析、化学风化强度、硅铝、铝铁硅风化系数比以及相对风化强度等的地球化学分析指标相一致,这也再次证明了我们采用石英颗粒表面形态特征分析手段的可行性和可靠性。 四、石英颗粒的裂变径迹年龄 三种类型石英颗粒的裂变径迹测年数据表明:a、同一样点石英颗粒裂变径年龄呈现一定的规律:F.T.AGE圆状、次圆状>F.T.AGE不规则状(棱状、次棱状)>F.T.AGE标准晶形(次生石英)。b、不同剖面的不规则状石英颗粒形成于同一个时期;不同剖面的圆状、次圆状石英颗粒形成于同一个时期。这两种石英颗粒不适于贵州碳酸盐岩风化壳的测年研究。c、不同剖面的标准晶形石英颗粒形成于不同时期,形成于碳酸盐岩酸不溶物原地堆积过程中,即与风化壳剖面同期形成,可用于贵州碳酸盐岩风化壳的测年研究。这一测量结果与我们对石英颗粒表面形态特征的观察、统计、分析结果相一致。 五、风化壳物源的新证据 贵州碳酸盐岩风化壳中的石英颗粒表面形态的分析结果表明,贵州碳酸盐岩风化壳的物质来源于碳酸盐岩中酸不溶物原地风化残积的产物,与其下伏基岩有着明显的继承性。这一分析结果与王世杰等人的碳酸盐岩酸不溶物的提取实验、地球化学、矿物学、粒度特征及区域地质背景等多方面的分析结果相一致,为贵州碳酸盐岩风化壳的物质来源及成因提供新的、更细致的证据。 六、贵州晚新生代地质-环境研究历史轮廓初建 由于目前对贵州及周边地区的风化-气候研究相对缺乏,数据资料较稀少,还没有形成完整的系统,我们本次研究也是建立在对风化壳中次生英颗粒年代学研究的基础上,研究还不是很透彻,因此只能对地质-环境研究历史轮廓进行初建。本文根据本次研究剖面土层中晶体次生石英颗粒的裂变径迹年龄分布情况,结合前人已有资料,对贵州25Ma以来的地质-环境演化历史的轮廓进行初建。从次生石英裂变径迹年龄值来看,中新世以来贵州主要经历了如下构造-风化期:25-19Ma、16-13Ma、10-6.5Ma、5-2Ma、1.7-1Ma。

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元素在矿物中的扩散作用,对其在地质体中的配布有着重要影响,被越来越多的用来解决地球化学动力学方面的问题。稀土元素(REE)能反映重要的地球化学信息,作为地球化学的示踪剂被广泛应用于探讨各类岩石成因和矿床成因。因此,查明REE在矿物中的扩散行为对于地学研究具有重要意义。 前人对元素(如O、Ar等)在不同矿物中扩散行为的理论研究,大多采用的是矿物晶格单独制约扩散速率的模型,由于稀土元素的离子半径各不相同,用此类模型来探讨其在不同矿物中的扩散行为是不合适的。为了寻求获取矿物中稀土元素扩散参数的简捷途径,本博士论文通过对前人关于矿物中REE扩散作用研究的实验结果进行分析归纳,探讨了扩散体系不同因素对扩散行为的控制规律。在此基础上,使用多元统计分析方法建立了预测REE在不同矿物中扩散参数的多变量模型,由此模型计算的1atm、无水环境下REE的扩散参数与实验测定结果在实验误差范围内相当吻合。与前人的模型相比,多变量模型能更全面地反映扩散体系各因素对扩散速率的制约。 此外,为了检验白钨矿Sm-Nd同位素定年方法的可靠性,本论文从不同角度进行了研究: (一) 理论验证 矿物内部的微量元素信息能否有效保存,在很大程度上取决于其扩散速率,因此本文从扩散动力学角度对白钨矿Sm-Nd同位素体系的封闭性进行了探讨。通过理论计算并结合实验模拟验证的方式获得了白钨矿中Sm、Nd的扩散参数,得出在1atm、无水环境下Sm和Nd的扩散方程为: Nd:D=4.00exp(-438kJmol-1/RT)cm2/s Sm:D=1.85exp(-427kJmol-1/RT)cm2/s 借助这些扩散数据,对白钨矿中Sm-Nd信息受扩散作用的影响程度做了分析。结果表明,在大多数地质环境下,Sm、Nd在白钨矿晶体中的扩散速率很低,同位素体系容易保持封闭不受热力学作用的影响。 (二) 地质验证 以湘西沃溪Au-Sb-W矿床为研究对象,通过对不同矿体的白钨矿进行Sm-Nd同位素年龄测定,将其结果与其它同位素方法得到的年龄数据以及野外地质关系、区域构造演化等进行了对比。结果表明,沃溪Au-Sb-W矿床的白钨矿Sm-Nd年龄结果与Ar-Ar年龄是一致的,与野外地质关系及区域构造演化特征等也相当吻合。 通过本论文的工作,得出以下主要成果和认识: (1)首次建立了适合于计算REE在不同矿物中扩散参数的理论模型,为研究矿物中REE的扩散行为提供了可靠的理论方法。 (2)首次获得了白钨矿中Sm-Nd的扩散参数,探讨了白钨矿中REE的扩散性质,并建立了1atm、无水环境下Sm和Nd在此矿物中的扩散方程。 (3)通过扩散动力学研究,得出白钨矿中Sm-Nd同位素体系的封闭性较为理想,为评价Sm-Nd同位素方法是否适合于制约白钨矿的成矿年龄提供了理论依据。 (4)通过不同同位素定年结果的比较以及与野外地质关系、区域构造演化等的对比,得出白钨矿Sm-Nd同位素年龄结果是真实有效的,从矿床学角度为评价该同位素定年方法的可靠性提供了实践证据。

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Grattan, J.P., Al-Saad, Z., Gilbertson, D.D., Karaki, L.O., Pyatt, F.B 2005 Analyses of patterns of copper and lead mineralisation in human skeletons excavated from an ancient mining and smelting centre in the Jordanian desert Mineralogical Magazine. 69(5) 653-666.

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McLaren, S. Gilbertson, D. Grattan, J. Hunt, C. Duller, G. Barker, G. Quaternary palaeogeomorphologic evolution of the Wadi Faynan area, Southern Jordan. Palaeogeography, Palaeoclimatology, Palaeoecology. 2004. 205. pp 131-154

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Grattan, J., Huxley, S., Karaki, L. A., Toland, H., Gilbertson, D., Pyatt, B., Saad, Z. A. (2002). 'Death . . . more desirable than life'? The human skeletal record and toxicological implications of ancient copper mining and smelting in Wadi Faynan, southwestern Jordan. Toxicology and Industrial Health, 18 (6), 297-307.

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Sims-Williams, P. (2002). The Celtic Inscriptions of Britain: Phonology and Chronology, c. 400-1200. Publications of the Philological Society, 37. Oxford: Blackwell Publishing. RAE2008

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Poolton, Nigel; Ozanyan, K.B.; Wallinga, J.; Murray, A.S., (2002) 'Electrons in feldspar II: a consideration of the influence of conduction band-tail states on luminescence processes', Physics and Chemistry of Minerals 29(3) pp.217-225 RAE2008

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Dissertação apresentada à Universidade Fernando Pessoa como parte dos requisitos para a obtenção do grau de Mestre em Psicologia, ramo de Psicologia Clínica e da Saúde

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Dissertação apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Criminologia

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Ballineaspig, anglicised Bishopstown, consists of two townlands which are Ballineaspigmore and Ballineaspigbeg. Taken together, both townlands oc­cupy an area identifiable in modern day terms as lying approximately be­tween the old Glasheen National School on the east side and what was, until recently, the University Farm Curraheen Road on the west. A townland is the smallest administrative land division in Ireland. Historians and other scholars are as yet inconclusive about the origins of these divisions. They are certainly as old as the seventeenth century. The townland with which this booklet is concerned is known as Ballineaspigmore. It extends west from the new Regional Hospital at Wilton and includes modern housing estates such as Uam-Var, Benvoirlich and Firgrove. The simplest translation of the townland name is the large land division of the bishop. To clarify a popular misconception, Bishopstown does not derive its name from the fact that in the early eighteenth century a bishop of Cork built his country residence there. The name is much older and can be found in sources dating back to the sixteenth century.