The Characteristics of the Hydrothermal Exhalative Dolostone of Lucaogou Formation in Santanghu basin and its Geology Setting Indication

The NW-SE trending Santanghu basin is located in Xinjiang,NW China,between Tianshan Mountains and Altai Mountains.The tectonic evolution history of north Xinjiang has long been debated,especially the question when did that area began its intraplate rift evolution stage.This abstract discusses the features and possible origin of the hydrothermal exhalative dolostone of Lucaogou Formation in Santanghu basin,aiming to provide relevant information about this question.The target dolostone are characterized by extreme thin lamina of 0.3cm–1 cm thick.Dolomite,ankerite,potassium feldspar and analcite are dominant composition.Most dolomite is poor crystallized and is in anhedral or subhedral shapes.Ankerite is generally porphyritic,few is in irregular shapes.It has to be noted that the porphyritic ankerite commonly develop zonal textures characterized by rings with various Fe O content.Potassium feldspar and analcite(50%)are commonly observed in dolostones.Thin sections show some analcite is tetragonal trisoctahedron with harbour–like corrosion rims.Besides,few fragments of carbonatite rocks are observed in Lucaogou Formation and they perform intermittent or scattered distribution in rock layers.Previous work done by our study team showsδ13C PDB values are 4.8‰~11.4‰,6.93‰on average.Theδ18 O PDB values are between-5‰~-21.1‰,-10.94‰on average.Paleosalinity calculated byδ13C andδ18 O is between 128.35 and 136.81,134.42 on average.Sr content of dolostones in study area reaches to164×10-6~537×10-6(379.1×10-6 on average),most dolostone in target area are between 0.70457~0.706194, average at 0.705360.Considering either accompanying residual tuff or residual leucite is found via electron probe,this indicates the analcite may derive form analcime phonolite.Furthermore,fragments of carbonatite rocks proves mantle-derived magmatism exist.The rapid variation ofδ18 O indicates multiple interactions of hydrothermal fluids with lake water during Lucaogou sedimentary period.87Sr/86Sr values are much lower than that of crustal silica rocks while are more close to mantle derived rocks,which indicates diagenetic hydrothermal fluid is mantle-origin.It has been reported that dolostone does not intergrow with iron-rich dolostone in study area.According to the latest X diffraction results of cores,iron-rich dolostone distributes rather locally.Given that ankerite commonly develop zonal textures characterized by various Fe O content,we confirm it is due to multiple hydrothermal fluids activities in different hydrothermal vents.There should be abundant hydrothermal vents during Lucaogou period.Deep faults and its relevant fractures built plenty paths for mantle-origin hydrothermal fluids to run up.Different vents owned various fluid properties,so did relevant sedimentation products.Hence we inclined to believe Santanghu basin was at intraplate rift evolution stage,under regional extension condition in late Carboniferous.During early-mid Permian the basin was a starved,deep lacustrine intracontinental rift basin.Accordingly,in northern Xinjiang,ocean basin may close in late Carboniferous and started continental sedimentary development in early Permian.     

太康M_S4.7地震目标区浅层结构探测

2010-10太康地区发生的M_S4.7地震和许昌-太康断裂的活动构造有关,而许昌-太康断裂在地表未留下任何构造痕迹,处于隐伏构造和隐伏活动状态。为了研究该区域的地壳浅部结构、断裂的空间展布及断裂的活动性,2015-10在太康县城以西震中区域完成了3条跨许昌-太康断裂的浅层地震反射剖面。结果表明,在深度1 000m以内,地震剖面揭示了5条断裂特征清楚的正断层,其中位于剖面南部向北倾的4条断层和位于剖面北部1条向南倾的断层形成相向倾斜关系,剖面上能分辨的断裂深度在75~150m之间,到达第四系地层,并且处于活动构造状态,这些断层可能和太康多次发生的地震有关。     

基于城镇化背景下的城郊土地利用模拟研究——以广州市花都区为例

本文以广州市花都区1990年和2008年TM影像作为数据源,在分析花都区2个时期土地利用格局时空特征的基础上,结合人工神经网络与元胞自动机(ANN-CA)模型对研究区的土地利用空间布局进行模拟。研究表明:根据研究需求构建的ANN-CA模型在实际模拟过程中无需人工定义模型结构和转换规则,只需通过3层神经网络即可模拟复杂的城市形态。因此,通过构建ANN-CA模型对土地利用空间布局进行模拟,可以合理预测城市土地利用发展趋势,具有较强的科学性和可靠性。     

无迹卡尔曼滤波衰减记忆算法研究

无迹卡尔曼滤波算法作为典型的卡尔曼滤波改进算法,有效地解决了线性化时高阶项的舍弃误差和强非线性模型的无法线性化问题。但是常规的无迹卡尔曼滤波对旧的数据和当前数据的利用率是相同的,很容易导致滤波的发散。通过引进衰减因子加强了对当前数据的利用,降低了旧数据对滤波结果的影响。本文基于此提出了衰减记忆无迹卡尔曼滤波算法,并对衰减因子的确定进行了分析。仿真试验分析表明,衰减记忆无迹卡尔曼滤波算法能够提高滤波结果的精度。     

Distribution of living radiolarians in spring in the South China Sea and its responses to environmental factors

Using a planktonic net(62-?m mesh) and a Rose-Bengal staining method, we studied the spatial distribution of living radiolarians in spring along two sections of the South China Sea(SCS) in spring and discussed the responses of living radiolarian distribution to tropical environmental factors. Generally, the highest abundance of living radiolarians occurred at the depth range of 25–75 m, where the chlorophyll-a maximum and the highest primary productivity were. In contrast, the maximum living abundance occurred in the top 25 m in cold eddies in the open seas and the abundance decreased with depth. We found that the inhibition effect of changing salinity(due to runoffs) on living radiolarians was much stronger than the promotion effect of mesoscale cold eddies. We observed that large variation of temperature was unfavorable for living radiolarians. The dominant species composition consisted of tropical-subtropical warm species. We identified some indicator species for tropical environments. Living Didymocyrtis tetrathalamus tetrathalamus could be an indicator for tropical surface water or mixed-layer water, and even for tropical oligotrophic water. Living Tetrapyle octacantha could be used to indicate tropical thermocline and eutrophic environment. Living Acanthodesmia vinculata could indicate tropical surface and subsurface waters. T. octacantha and A. vinculata should only be used as indicators for upwelling in the open seas, i.e., far away from river mouths. Living Siphonosphaera polysiphonia preferred to form colonies, which might be related to the effect of warm eddies. Living Cyrtopera laguncula and living Cornutella profunda occurred in the tropical upper layer, even in the surface layer, which suggests that they should not be used as indicators for intermediate and deep waters.     

基于邻域扩展量化法的城市边界识别

城市空间分析的基本条件是可靠的测度,而城市的基本测度是规模。客观定义城市边界是有效确定城市规模的技术前提。近年来国内外学者提出几种城市边界识别的方法,其中能够定量反映城市内部实体空间组织关系的多采用矢量图像。但这些矢量数据的获取十分困难,且实时性差。因此,本文借鉴前人的研究成果,基于邻域扩展量化和标度思想,提出一种应用于遥感栅格图像上的城市边界识别方法。该方法的本质是一种空间邻域融合法,通过改变像元邻域的作用范围,可以得到不同的空间集群数目;借助搜索范围与集群数目的标度关系确定一个客观的半径,据此可以利用GIS技术确定城市边界。将该方法应用于北京地区多个年份的遥感图像,发现了像元的有效邻域作用范围。此方法以栅格图像为基础,数据实时性好并且获取容易,计算过程简便,在未来的城市边界研究过程中,可望与现有的方法相互补充。     

金属矿山阶段嗣后充填胶结充填体矿柱力学模型分析

矿柱宽度和充填体自立高度是阶段嗣后充填顺利实施的重要影响因素。基于弹性力学平面应变基本假设,建立阶段嗣后胶结充填体矿柱力学模型并进行理论求解。以某铁矿为工程分析实例,采用控制变量法（CVM）研究矿柱不同宽度、高度条件下,水平应力和剪应力的变化规律。研究表明：矿房极限宽度和高度分别为19.8 m和103.2 m。胶结充填体矿柱水平应力随矿柱高度的增高而逐渐增大;剪应力在矿柱中心位置达到最大,且高度越大,剪应力值也越大。在胶结充填体矿柱与非胶结充填体接触侧剪应力趋于定值。矿柱宽度分别为15、18、20 m时,其剪应力分别为243.8、292.6、325.1 kPa。而产生剪应力的主要原因是非胶结充填体受水平应力作用在与胶结充填体矿柱接触面产生滑动摩擦力所致。     

藏北羌塘盆地早侏罗世-中侏罗世早期沉积构造特征

侏罗纪早期是研究羌塘盆地形成过程、判别盆地性质的重要时期.通过开展早侏罗世-中侏罗世早期的沉积相、古流向、沉积厚度统计等分析,恢复了该时期羌塘盆地的古地理面貌,提出了侏罗纪早期羌塘盆地并非前陆盆地,而是伸展构造背景下形成的裂陷型盆地.该时期盆地以中央隆起带为界,南部为陆缘开阔海盆地,形成滨岸-浅海陆棚相碎屑岩沉积;北部为陆缘近海湖盆,成盆初期(托尔期)发生强烈的裂陷活动,形成一套火山碎屑岩沉积体系,可识别出三个北西向分布的裂陷槽,巴柔期快速下沉,沉积一套厚达2 000 m以上的冲积扇-湖泊三角洲-湖盆相碎屑岩夹少量灰岩和石膏沉积,沉降中心位于湖盆南部,表现出明显的继承性,随后逐步向北东迁移,海水自中央隆起带中段频繁向湖盆浸漫.巴通期中央隆起带进一步下沉,南、北羌塘连成一个统一的拗陷盆地,从此沉积作用进入稳定发展阶段,形成稳定的碳酸盐岩台地沉积体系.     

石英的热释光特征及其在测年中的应用

１热释光测年的基本原理自从１６６３－１０ＲｏｂｅｒｔＢｏｙｌｅ在英国皇家科学院描述了他所发现的钻石夜发光现象,即标志着人们首次揭示了热释光现象。目前,结晶固体的释光（磷光）现象被广泛应用于年代的测定。人们在应用释光技术测定各种不同类型矿物的年龄时,都...     

Tides and short-term variabilities in the Kuroshio west of Yonakuni-jima

INTRODUCFIONTheKuroshioeastofTaiwanIslandflowsnorthwardandenterstheEastChinaalgathroughapaSSagebetweenTaiwanIslandandlriomote-shima.TOstudyfurthertheKuroshiothereandestimateitstransPOrt,itisnecessarytoobservetheKuroshioCurrentdirectly.Therehavebeen*ThisstudywassupportedbytheNationalNaturalaudienceFoundationofChinaundercontractNo.49476278.severaldirectobservationsoftheKuroshionearTaiwanIsland.Forexample,thedirectcurrentmeasurementat(24'24'N1123'35'E)byinabaetal.(1981)showedtheapp…