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41.
Rhys G. O. Timms Ashley M. Abrook Ian P. Matthews Christopher P. Francis Agnieszka Mroczkowska Ian Candy Stephen J. Brooks Alice M. Milner Adrian P. Palmer 《第四纪科学杂志》2021,36(3):339-359
The influence of the North Atlantic on the margins of Europe means the region is particularly sensitive to changes in the ocean–atmospheric system. During the Last Glacial–Interglacial Transition (16–8 cal ka bp ) this system was repeatedly disrupted, leading to a series of abrupt and short-lived shifts in climate. Despite much research, the number and magnitude of these ‘centennial-scale’ events is not well understood. To address this, we expand upon investigations at Quoyloo Meadow, Orkney, Scotland, one of the best chronologically constrained palaeoclimate records in northern Britain. By coupling stable isotope and chironomid fossil analyses with existing data, this study identifies multiple phases of centennial-scale disturbance at: c. 14.0, 11.1, 10.8, 10.5, 10.45 and 10.3 cal ka bp , with the events at 14.0 and 10.3 exhibiting a particularly pronounced cold-climate signature. During the Holocene, the strongest response to climate forcing was at c. 10.3–10.0 cal ka bp , expressed as a two-stage drop in mean July temperatures, a shift in pollen spectra indicative of ‘less-stable’ climatic regimes, and a depletion in δ18O values. We interpret this as the first reliably dated incidence of the ‘10.3-ka event’ in the British Isles and consider the wider impact of this climatic reversal in other Holocene records. 相似文献
42.
对产自河北围场下白垩统九佛堂组的65件鲎虫化石标本进行研究。根据其形态特征,认为这些鲎虫化石属于三角围场鲎虫(Weichangiops triangularisYang et Hong, 1980)。有观点认为,具有上肛板的鲎虫为冷水型鲎虫,而不具上肛板的鲎虫为暖水型鲎虫。河北围场采集的鲎虫化石有的具上肛板,有的不具上肛板,目前没有任何证据表明其为冷水型鲎虫与暖水型鲎虫混生的产物。通过研究,对三角围场鲎虫的特征进行了适当修正,认为围场地区的鲎虫化石具1对复眼,因此依据单个复眼而建立的新亚科——围场鲎虫亚科(Weichangiopsinae)不成立,应予以摒弃。三角围场鲎虫存在明显的性双形现象,雄性个体尾部具有上肛板,雌性个体不具有上肛板,这对于鲎虫化石分类研究具有重要的科学价值,可避免在生物分类时发生同物异名现象。 相似文献
43.
Houfangzi graphite deposit is located in the middle of the graphite metallogenic belt in the northern margin of North China Block in Hebei Province, which belongs to regional metamorphic type graphite deposit. In this paper, through rock-mineral determination, IP ladder sections and exploratory trench survey, the authors have discussed its metallogenic geological characteristics and ore body characteristics, and analyzed its ore genesis. The research results show that the ore bodies are mainly in the graphitic marble of Dongjingzi Formation of Hongqiyingzi Group, which are stratified and controlled by layers, with NE trend and NNW inclination. The IP anomaly shows that Houfangzi graphite deposit is characterized by low resistance and high polarization. Ore bodies are stable and of big scale, and their fixed carbon content ranges from 1.42% to 3.28%, which has the potential to be a large graphite deposit. The ore-forming material came from granulite and graphite marble, while the regional metamorphism is the main mineralization of Houfangzi graphite deposit, with the enrichment and increasement caused by late magmatic activity and migmatization. 相似文献
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深入挖掘气象站点的观测降雨数据,研究区域降雨的雨型规律,对于洪涝灾害预警和减灾措施制订有重要意义.本文基于河北省2005-2017年3189个站点逐小时降雨观测数据,进行"场雨"的划定,进而提取历史上各场雨的累积雨量、时长指标.采用数据挖掘技术中的DTW相似性算法进行场雨雨型的自动归类,将场雨分成Ⅰ-Ⅶ共7种雨型,包括... 相似文献
47.
河北中关铁矿是“邯邢式”矽卡岩铁矿的代表矿床,本文将中关铁矿床成矿过程划分为5个阶段:干矽卡岩阶段、湿矽卡岩阶段、氧化物阶段、铁铜硫化物阶段和铅锌硫化物阶段。对湿矽卡岩阶段、氧化物阶段和铁铜硫化物阶段的金属矿物(包括黄铁矿、磁铁矿、赤铁矿等)开展电子探针测试,并且对这三个成矿阶段的代表性磁铁矿进行LA-ICP-MS微量元素测试,旨在查明中关铁矿床中Co的赋存状态以及在矿床不同成矿阶段的分布规律,探讨Co元素迁移演化-沉淀机制。研究结果表明,Co主要以类质同象的形式存在于黄铁矿中。不同成矿阶段的Co元素分布不均匀,氧化物阶段黄铁矿和磁铁矿中的Co含量最高,分别为0.12%~1.39%、41×10-6~76×10-6;铁铜硫化物阶段黄铁矿大量出现,且Co含量相对较高,为BDL~0.45%,同时期条带状磁铁矿为32×10-6~71×10-6,故此阶段为Co元素最主要的富集阶段。湿矽卡岩阶段为较高温、弱氧化条件,氧化物阶段温度逐渐降低,氧逸度增加,Co可能主要以CoCl42?形式络合迁移;铁铜硫化物阶段温度进一步降低,但还原性增加,Co可能主要以CoCl42?和Co(HS)+形式络合迁移。温度降低以及氧化还原条件的变化可能是控制Co沉淀的重要因素。 相似文献
48.
冀北地区是河北省矿产资源重要聚集地之一,成矿条件优越,其中中-酸性侵入岩体与银铅锌多金属矿床成矿密切相关。然而,大量的第四系覆盖压制了一些深部及隐伏弱异常成矿信息,使得常规化探方法在该覆盖区提取效果微弱。本文运用奇异性分析及主成分分析对冀北1:20万水系沉积物常量元素化探数据进行分析处理,提取区内成矿元素弱异常,并将其与未进行奇异性处理的结果进行对比。结合区域地质背景、物化探资料圈定覆盖区内与中-酸性侵入岩体有关的异常区,对成矿作用、成矿规律进行分析、讨论,以期揭示区内元素富集规律。结果显示,上述组合方法可以有效提取元素弱异常并进行成矿有利区圈定,并且圈定位置与已知岩体位置、区域构造条件相吻合,共圈出隐伏异常点7个,推测其为成矿远景区。 相似文献
49.
Rosalind C. King Guillaume Backé Christopher K. Morley Richard R. Hillis Mark R.P. Tingay 《Marine and Petroleum Geology》2010
Recent GPS measurements demonstrate that NW Borneo undergoes 4–6 mm of plate-scale shortening a year, which is not accommodated by plate-scale structures. The only geological structure in NW Borneo described to accommodate on-going shortening is the Baram Delta System located on the outer shelf to basin floor. Delta toe fold-thrust belts are commonly thought to be caused by margin-normal compressional stresses generated by margin-parallel upslope gravitational extension. 相似文献
50.
Seismic reflection data indicate the Moroccan salt basin extends to the Cap Boujdour area in the Aaiun Basin. Two salt diapir structures have been identified and several areas of collapsed strata indicate probable salt removal at the shelf edge. The presence of salt in this area correlates to the conjugate southern George's Bank Basin and the Baltimore Canyon area, and it is suggested that the salt extends southward from the known salt diapir province in the George's Bank Basin southward to the Great Stone Dome. The paucity of salt diapirs is attributed to the thick carbonate and anhydrite sequence, which was deposited soon after salt deposition that inhibited halokinesis. The presence of salt along this large segment of the Atlantic margin should increase its hydrocarbon potential with traps created around salt diapirs and provision of migration pathways from deep potential source rocks in the early Cretaceous and Jurassic strata to shallower levels. 相似文献