赣东北茶坑花岗斑岩锆石U-Pb年代学、地球化学特征及地质意义

赣东北茶坑花岗斑岩及围岩中发现了白钨矿化。为了进一步查明钨矿化与花岗斑岩的关系及其成矿潜力,对花岗斑岩开展了锆石U-Pb年代学、岩相学及地球化学研究。结果表明:茶坑花岗斑岩的形成年龄为153~152 Ma;具有高硅(SiO2含量为74.62％~76.09％)、富碱(Na2O+K2O含量为7.14％~8.55％)、富钾(K2O含量为4.95％~5.69％)、强过铝质(A/CNK为1.17~1.39,平均值为1.3)的特征;微量元素相对富集Rb、U、K,亏损Ba、Sr、P、Ti;稀土元素总含量为(62.52~75.13)×10-6, (La/Yb)N=3.73~12.16,平均值为7.81,轻、重稀土元素分馏明显,且相对富集轻稀土,具有中等程度的Eu负异常(δEu为0.55~0.82)。茶坑地区花岗斑岩的W含量为(8.80~160)×10-6,平均值为51.16×10-6,是华南花岗岩W平均含量的15倍,表明该地区花岗斑岩具有形成斑岩型-石英脉型钨矿的潜力。     

不同温度下抑食金球藻、中肋骨条藻和海洋卡盾藻间的相互作用

本文选取抑食金球藻(Aureococcus anophagefferens)、中肋骨条藻(Skeletonema costatum)和海洋卡盾藻(Chattonella marina)三种藻在20℃和25℃下进行单种、两种或三种藻间的培养实验, 探究在不同温度下藻种间的相互作用和竞争优势。单种培养结果显示抑食金球藻和中肋骨条藻对温度25℃敏感, 其环境容量(K)被显著降低; 而海洋卡盾藻的內禀增长率(r)在25℃下显著升高, 但K保持不变。在共培养中, 海洋卡盾藻在20℃下因抑食金球藻添加致死, 但在25℃处理下其K值上升120%。虽然中肋骨条藻的r在两个温度下均受海洋卡盾藻添加的促进, 但其K值从20℃下的上升43%转变为25℃下的降低48%。温度变化对于抑食金球藻和中肋骨条藻共培养的结果无明显影响, 中肋骨条藻的K均上升40%, 而抑食金球藻的K值均下降60%~70%。结果说明, 种间竞争除了共培养藻固有的相互作用关系因素外, 也受到微藻间温度适应性差异的影响。在20℃条件下三种藻混合, 抑食金球藻K的抑制率达到最高为79%, 而中肋骨条藻K的促进率达到最高为108%, 这可能表明三者之间的相互作用存在协同效应。     

Anatomy and sedimentary model of a hooked spit (Sylt,southern North Sea)

A sedimentary model for hooked spit depositional systems based on ground‐penetrating radar and sedimentological data is presented. The recurved main spit of Sylt Island (southern North Sea) is dominated by migrating sand dunes; the investigated hooked spit exhibits a system of foredune ridges, oriented perpendicular to the dunes of the recurved spit. The development of the hooked spit is related closely to the presence of an adjacent tidal inlet, where strong tidal currents and a steep bathymetry prevent a further northward progradation of the main spit and trigger a deflection from northerly‐directed to easterly‐directed net sediment transport. Ground‐penetrating radar data and shallow sediment cores reveal the sedimentary architecture of the hooked spit in high resolution and allow the proposition of a genetic stratigraphic model. It is shown that the growth of the hooked spit is controlled by the interplay of alongshore migrating foreshore beach drifts under fair‐weather conditions and strong erosional events, interpreted as the result of rare severe storms. These storms may excavate scarps in the backshore, which play an important role in the development of foredune ridges. Accelerator mass spectrometry ¹⁴C ages indicate an absolute age of at least 1300 years for the hooked spit, which possibly correlates with strengthened erosion of the main spit. In contrast to the main spit, where the sediment budget is negative nowadays, growth of the hooked spit beach accelerated significantly during the last decades. This effect can probably be attributed to enhanced beach‐nourishments updrift along the main spit and makes the investigated hooked spit a natural laboratory to study the influence of increasing sediment supply into a system developing under the conditions of sea‐level rise. The study shows that the same external forces lead to distinct progradational processes along one barrier‐spit system.     

黑龙江省海伦市农耕区土壤硒分布特征及影响因素

海伦市是黑龙江省耕地面积最大的县市,为了研究海伦市农耕区土壤硒的分布特征及影响因素,在海伦市农耕区采集了15 608件0~20 cm表层土壤样品和976件150~200 cm深层土壤样品,分析了土壤全硒含量、形态等土壤化学指标。结果表明,表层土壤硒元素含量在0.02~0.87 mg·kg^-1之间,平均含量0.29 mg·kg^-1,93.87%的农耕土壤为足硒土壤,4.99%的土壤为富硒土壤,几乎不存在硒潜在不足和缺硒土壤,无硒中毒地区。不同土壤类型的硒元素平均含量由高到低依次为水稻土>黑土>草甸土>风沙土>暗棕壤。相关分析结果表明:影响研究区土壤硒含量的主要因素是土壤pH、有机质和成土母质,土壤中硒元素赋存形式以有机结合态为主,土壤总硒、有机质、pH也是影响硒有效性的主要因素。     

面向配网带电作业机器人的激光雷达与视觉系统融合定位

为提高配网带电作业机器人在开展带电作业时对导线的识别与定位的准确性,本文提出了一种基于单线激光雷达传感器与视觉系统融合的定位方法,获取导线的空间三维坐标.并通过研究多传感器在户外强光环境下的工作特点,提出了基于激光雷达深度信息与图像信息的多传感器融合算法.首先利用激光雷达与相机事先进行像素级标定,使图像像素与激光雷达深...     

巴基斯坦Bahawalpur黄土岩石磁学特征及磁化率变化机制研究

风成黄土是陆地上分布最广泛的沉积物之一,记载了各种古气候演化信息.目前巴基斯坦的黄土研究甚少,磁化率与气候对应的变化机制研究尚未开展.本文对位于巴基斯坦印度河平原Bahawalpur地区新发现的黄土-古土壤剖面进行系统的岩石磁学研究,结合粒度和漫反射光谱(DRS)数据,讨论巴基斯坦黄土的磁化率变化机制.实验结果显示：Bahawalpur (BH)剖面黄土层主要的载磁矿物为磁铁矿,同时含有少量磁赤铁矿和针铁矿,磁性颗粒以原生的MD和PSD颗粒为主.相对于黄土层,古土壤层则是以针铁矿为主,含有顺磁性矿物和少量磁铁矿.BH剖面磁化率与成土作用关系和中国黄土高原典型剖面相反,磁化率的变化可能存在一个阈值12.8×10^-8m³·kg^-1,在阈值之上,强磁性矿物(磁铁矿、磁赤铁矿)占主导;阈值之下,以弱磁性矿物(主要是针铁矿)为主,这种磁性矿物的转变可能导致磁化率降低.本文可为今后利用磁化率解读该地区地层蕴含的古气候信息提供新线索.

     

The Carancas meteorite impact crater,Peru: Geologic surveying and modeling of crater formation and atmospheric passage

Abstract— The recent Carancas meteorite impact event caused a worldwide sensation. An H4–5 chondrite struck the Earth south of Lake Titicaca in Peru on September 15, 2007, and formed a crater 14.2 m across. It is the smallest, youngest, and one of two eye‐witnessed impact crater events on Earth. The impact violated the hitherto existing view that stony meteorites below a size of 100 m undergo major disruption and deceleration during their passage through the atmosphere and are not capable of producing craters. Fragmentation occurs if the strength of the meteoroid is less than the aerodynamic stresses that occur in flight. The small fragments that result from a breakup rain down at terminal velocity and are not capable of producing impact craters. The Carancas cratering event, however, demonstrates that meter‐sized stony meteoroids indeed can survive the atmospheric passage under specific circumstances. We present results of a detailed geologic survey of the crater and its ejecta. To constrain the possible range of impact parameters we carried out numerical models of crater formation with the iSALE hydrocode in two and three dimensions. Depending on the strength properties of the target, the impact energies range between approximately 100–1000 MJ (0.024–0.24 t TNT). By modeling the atmospheric traverse we demonstrate that low cosmic velocities (12–14 kms^?1) and shallow entry angles (<20 °) are prerequisites to keep aerodynamic stresses low (<10 MPa) and thus to prevent fragmentation of stony meteoroids with standard strength properties. This scenario results in a strong meteoroid deceleration, a deflection of the trajectory to a steeper impact angle (40–60 °), and an impact velocity of 350–600 ms^?1, which is insufficient to produce a shock wave and significant shock effects in target minerals. Aerodynamic and crater modeling are consistent with field data and our microscopic inspection. However, these data are in conflict with trajectories inferred from the analysis of infrasound signals.     

Petrographic and petrophysical investigation on carbonate samples (Upper Cretaceous) from the Tushka Area (Egypt) with special focus on the effective pore radius

Petrographic and petrophysical properties of 42 carbonate rock samples from the Tushka Area, Egypt have been investigated. The samples originate from the Upper Cretaceous taken from seven shallow wells and were subdivided into three microfacies. The petrographic characterization of the glauconite-rich, fossiliferous limestones was carried out over 17 thin sections and an additional measurement of the glauconite content by color differentiation. The facies were characterized as (1) oolithic, low-dolomitic, and low-glauconitic, fossil-rich packstone with a tendency towards floatstone or rudstone; (2) glauconite-rich, low-dolomitic floatstone with a tendency towards rudstone; and (3) glauconite and iron mineral-rich, sparry calcitic cemented, and low-dolomitic rudstone. The petrophysical investigation providing grain density, porosity, electrical conductivity, specific internal surface, permeability, magnetic susceptibility, and the pore throat geometry supports the classification into three facies. A strong relation between permeability and formation factor is observed. The median pore radius derived from mercury porosimetry proves to be a good estimate of the effective hydraulic radius. An increased content of iron oxides was identified in facies 3. The increased iron content is related to higher values of both magnetic susceptibility and specific internal surface.     

胶东玲珑金矿田不同矿段构造变形岩相带特征与深部找矿预测

大规模勘探结果表明,胶东主要金矿田深部存在第二富集带,显示深部找矿潜力巨大。"深部第二富集带"受什么因素控制,深部预测的目标是什么,成矿边界在哪里,这些关键问题值得深入研究。结合"岩浆核杂岩隆起-拆离凹陷"构造系统和"米字型"构造控矿模式,提出将"构造变形岩相带"作为深部找矿预测目标和成矿边界,建立新的深部找矿预测标志。以玲珑矿田为例,综合对比各矿段3个主要方向(NEE、NE、NNE)构造变形岩相带的空间分布、物质成分、结构构造、形成时间、成岩成矿深度等特征,总结矿化富集规律及其向深部的变化趋势,探讨不同方向构造变形岩相带的时空演化关系。从"深部第二富集带"发育程度看,这些已知构造变形岩相带的深部都有找矿潜力,其外围可能存在平行的、更大深度的构造变形岩相带。