High stress late Maastrichtian – early Danian palaeoenvironment in the Neuquén Basin, Argentina

During the late Maastrichtian to early Danian the Neuquén Basin of Argentina was adjacent to an active volcanic arc to the west and an extensive land area to the northeast. Mineralogical and geochemical studies of the Bajada del Jagüel in the Neuquén Basin indicate a generally warm climate with seasonal changes in humidity and an open seaway to the South Atlantic that maintained marine conditions. Biostratigraphic and quantitative foraminiferal and nannofossil analyses indicate that sediment deposition during the late Maastrichtian (zones CF4-CF2, N. frequens) occurred in relatively shallow middle neritic (100 m) depths with largely dysaerobic bottom waters (abundant low O₂ tolerant benthics) and fluctuating sea level. Calcareous nannofossils indicate a high stress marine environment dominated by Micula decussata. Planktic foraminifera mimic the post-K/T high stress environment with alternating blooms of the disaster opportunists Guembelitria and low oxygen tolerant Heterohelix groups, indicating nutrient-rich surface waters and an oxygen depleted water column. The high stress conditions were probably driven by high nutrient influx due to upwelling and terrestrial and volcanic influx. The K/T boundary is marked by an erosional surface that marks a hiatus at the base of a 15-25 cm thick volcaniclastic sandstone, which contains diverse planktic foraminiferal zone P1c assemblages and nannofossils of zone NP1b immediately above it. This indicates deposition of the sandstone occurred 500 ky after the K/T hiatus. No evidence of the Chicxulub impact or related tsunami deposition was detected.     

基于自适应时序剖分与KNN的短时交通流量预测

在智能交通系统中,准确和高效的短时交通流量预测是交通诱导、管理和控制的前提。由于交通流量动态变化中表现出的时变性和非平稳性特征,其预测难度较大,是交通领域中亟待解决的难题。为提高短时交通流量的预测精度,本文设计与实现了基于自适应时序剖分与KNN（A-TS-KNN）的短时交通流量预测算法。① 基于动态时间规整（Dynamic Time Warping,DTW）动态剖分单日时序为不同的交通模式;② 在不同交通模式,采用互信息法求解每个预测时刻时间延迟的最大阈值,构造不同时间延迟的状态向量,生成交通流量历史数据库;③ 采用十次十折交叉验证的方法求解每个时刻不同时间延迟与不同K值的正交误差结果分布,提取误差最小的正交结果,得到自适应时间延迟与K值的参数组合;④ 采用K个最相似的近邻的距离倒数加权值作为预测结果。对比K近邻（K-nearest neighbors, KNN）、支持向量回归（Support vector regression,SVR）、长短期记忆神经网络（Long-short term memory neural network,LSTM）以及门控递归单元神经网络（Gate recurrent unit neural network,GRU）共4种主流预测模型,A-TS-KNN算法预测精度显著提升;将A-TS-KNN算法用于福州市城市路网中其他交叉路口的短时交通流量预测,结果表现出良好的泛化能力。     

撞击事件诱发核反应热力学过程及其在事件地质学研究中的意义

摘要：从大规模撞击事件的基本动力学和热力学公式推导出发,讨论了白垩纪－第三纪界线（Ｋ／Ｔ界线）事件能量随时间的释放过程,并对发生热核聚变反应的条件进行了分析。最后,还对其可能的事件地质学意义进行了讨论．     

珠江口表层水中主要常量离子的研究

９９４年９月采集了珠江口表层海水水样,并对其溶解态的Ｋ＋、Ｎａ＋、Ｃａ２＋、Ｍｇ２＋、ＳＯ２－４、Ｃｌ等化学要素进行了测定。结果表明,珠江口调查海域表层水中溶解态的Ｋ＋、Ｎａ＋、Ｃａ２＋、Ｍｇ２＋、ＳＯ２－４主要受陆源淡水与外海水物理混合稀释的影响,与Ｃｌ具有良好的直线正相关;Ｃａ２＋／Ｃｌ、ＳＯ２－４／Ｃｌ明显高于大洋水相应比值,Ｎａ＋／Ｃｌ、Ｍｇ２＋／Ｃｌ略高,而Ｋ＋／Ｃｌ比大洋比值低;在与中国其它各主要河口表层水对应Ｃｌ比较中,珠江口的ＳＯ２－４／Ｃｌ较高,而Ｃａ２＋／Ｃｌ,Ｍｇ２＋／Ｃｌ比值居低;上述各主要常量离子和Ｃｌ的等值线均沿自北向南走向递增。     

Chemical alternation of waters in the Kuroshio/Oyashio Interfrontal Zone

An intensive survey has been conducted of the distributions of some chemical properties (dissolved oxygen, nutrients and carbonate properties) in the Kuroshio/Oyashio Interfrontal Zone. Many low-salinity water patches were found down to depths of 640 m. Each chemical property also showed anomalies in these patches, but the degree of variation showed a low correlation with salinity. This may be due to the high variability of biological processes in the surface waters where these patches are formed. Vertical profiles of the chemical properties were also observed along the Kuroshio extension axis from 140.50°E to 146.75°E. The concentrations of nutrients and total carbonate (TC) in the water having densities greater than σ_θ=26.60 can be regarded as being formed by the isopycnal mixing of the Kuroshio component water and Oyashio component water and biological degradation within the density surfaces. This implies that the transport of chemical properties by the diapycnal mixing is negligible in these density layers in the K/O zone.     

Geomagnetic paleosecular variation at Hawaii around 3 Ma from a sequence of 107 lava flows at Kaena Point (Oahu)

We have sampled a sequence of 107 lava flows in the Waianae series on Oahu, Hawaii, in two separate stretches. The first (51 flows) at Kaena Point extends from sea level to an altitude of 190 m, and the second (56 flows) follows the Satellite Tracking Station road from 218 m to 360 m above sea level. Thermal and af demagnetization yield very similar results, and reveal only normal polarities. K/Ar dating at five different horizons combined with the paleomagnetic results indicate that the sequence was emplaced entirely in the normal polarity interval between the Upper Mammoth and the Lower Kaena polarity transitions (3.22–3.11 Ma). Some of the flows are serially correlated. Filtering does not, however, drastically affect the final results. Inclinations are shallower than those expected from a centered dipole field. Although large (13°), the inclination anomaly is consistent with results from other sites at the same latitude. The scatter of the VGPs about the geographic pole is consistent with available data from other regions at similar latitudes. The scatter of the directions is also consistent with the predictions of recent statistical models of paleosecular variation. Therefore, these results do not support the hypothesis of a Pacific dipole window.     

地球化学屏障中添加剂的选择研究

设置一系列加有不同添加剂的地球化学屏障,利用静态平衡实验,并与未加添加剂的空白实验对比,分析其对Ｕ,Ｃｏ,Ｓｒ的阻滞性能;并通过计算Ｋｄ值,对屏障的综合阻滞性能进行分析,选出恰当的添加剂。结果表明：ＮａＳ２作碱性－还原添加剂,利于核素的化学沉淀反应,而且Ｋｄ值显著地增加,屏障对Ｕ,Ｃｏ,Ｓｒ的阻滞性能最好。     

Investigation of trace metals distribution in water,sediments and wetland plants of K(i)z(i)l(i)rmak Delta,Turkey

In this study,accumulation and distribution of Pb,Cu,Zn,Co,Ni,Mn and Fe in water,bottom sediments and four plant species (Myriophyllum verticillatum,Hydrocharis morsus-ranae,Nymphaea alba and Typha latifolia) were investigated in (C)ernek Lake of Kizihrmak Delta.The Kizdirmak Delta is one of the largest natural wetlands of Turkey and it is protected by the Ramsar convention since 1993.Selected physico-chemical parameters such as pH,conductivity and dissolved oxygen and also trace metal concentrations were monitored in water.All the parameters obtained were found higher than that of the national standards for the protected lakes and reserves.The accumulated amounts of various trace metals in bottom sediments and wetland plants were found in the following order of Fe ＞ Mn ＞ Zn ＞ Ni ＞ Co ＞ Cu ＞ Pb and Fe ＞ Mn ＞ Zn ＞ Ni ＞ Co respectively.The historical trace metal intake of Myriophyllum verticillatum,Hydrocharis morsus-ranae,Typha latifolia and Nymphaea alba were obtained higher than that of the toxic metal levels and these plants may be accepted as accumulators for the detected trace metals and also bioindicators in the historically polluted natural areas.     

Influence of water logging time on the growth of candel seedlings

Influence ofwaterlogging time on the growth ofKandeliacandel(L.) Druce seedlings grown for 70 d in the artificial-tidal tanks' simulated semidiumal tide under greenhouse is studied. Sand and soil act as the substrate and artificial sea-water with salinity of 15 is used in cultivation. Shorter waterlogging time (inundated for about 2 ～ 4 h) promotes thegrowth of K. candel seedlings, while longer time(inundated more than 8 h) or no waterlogging(0 h) inhibits theirgrowth. The number and length of aerating roots increase with the increase ofwaterlogging time. Under existing condi-tions, the optimalwaterlogging time for the growth of K. canoel seedlings is about 2 ～ 4 h in every tide cycle. Com-pared with other treatments, the 2 h sanded treatments obtain the highest biomass of seedlings, have the lowest massloss ofhypocotyl and broaden the photosynthetic area by increasing the area per leaf after 70-d cultivation. And the soiltreatments have the similar tendeney. However, waterlogging for 8 h in every tide cycle is critieal for normal develop-ment of seedlings. K. candel seedlings are highly tolerant to waterlogging and a proper waterlogging is beneficial to thegrowth ofK. candel seedlings.     

粉质黏土填料在K30试验加载进程中的变形时间效应状态分析

变形稳定标准和分级加载制度是影响K30试验效率和准确性的关键因素,与加载进程中填土的变形时间效应状态密切相关。开展了3组最优含水率下压实系数K分别为0.90、0.95和1.00填土模型的小型平板载荷试验,获得了不同荷载作用下填土变形时程曲线和弹塑性变形数据,讨论了在K30试验加载进程中填土变形状态的变化及其对加载稳定时间的影响。试验表明：良好压实的粉质黏土填料,在K30试验进程中的变形以弹性为主,处于缓慢收敛状态,随着加载级数增加,塑性变形比例逐渐增大,变形时间效应呈现出由微弱进入明显状态的演化趋势,变形1.25 mm对应于缓慢收敛中的微弱时间效应亚状态;“变形速率不超过0.01 mm/min”变形稳定标准分级加载时间随时间效应指数呈加速增长规律,能在保证试验精度的基础上提高试验效率;以最大荷载下填土变形时间效应不应超过显著状态、变形量不小于1.25 mm为约束条件,针对5级加载、0.04 MPa荷载增量的加载制度,可得K30试验的适宜范围为60～160 MPa/m。