Organic matter and fine grains as possible determinants of spatial and seasonal variability in bed sediment fauna: A case study from a Hercynian gravel stream

The spatial and seasonal distributions of organic matter and fine grains were tested as possible determinants of fauna distribution in bed sediment of a Hercynian gravel stream. Invertebrate densities and the amounts of fine grains and organic carbon were assessed in freeze-core samples taken along 70 cm depth profiles at three different positions in the stream channel. Sampling was conducted on five occasions of low discharge over two years. The variability in invertebrate community composition was analysed using Detrended Correspondence Analysis with posterior projection of explanatory variables; Variation Partitioning was used to estimate the independent and shared effects of the explanatory variables. We found that the best predictors of the invertebrate community were spatial variables (depth, position in the channel) and then variables influenced by seasonal patterns (surface water temperature and discharge). The influence of organic matter and fine grain content was significant only after eliminating spatial autocorrelation. High amounts of organic matter, randomly accumulated in the sediment, improved the model by explaining high fauna densities. The fine grain content was not a limiting factor to fauna at our study site. It is possible that the large amount of mica flakes in the sediment has caused the arrangement of grains with a pore space sufficient for fauna even when fine grain content was high.     

Long-term denudation rates of actively uplifting hillcrests in the Boso Peninsula, Japan, estimated from depth profiling of in situ-produced cosmogenic Be and Al

Depth profiling of in situ-produced cosmogenic ¹⁰Be and ²⁶Al was applied to estimate the rate of long-term denudation on actively uplifting hillcrests made of weakly consolidated sandstone in the Boso Peninsula, Japan. The nuclide concentration in the topmost meter of the hillcrest has reached an equilibrium value owing to surface denudation at 90 mm/kyr. This rate is much smaller than the regional uplift rate, and is consistent with the current isolated residual topography of the hillcrest. By considering the epoch of emergence of the sandstone hillcrests, we estimate the summit denudation rate of the adjacent mudstone hill formation to be 720 ± 110 mm/kyr.     

用sPn震相计算震源深度的初步分析与应用

用近震震相sPn与Pn波的到时差测定壳内近震深度的方法简捷准确。本文对2004年3月24日内蒙古东乌珠穆沁旗5.9级地震震中1 000 km范围内不同台站记录的sPn震相进行了初步分析,计算了该次地震的震源深度。还讨论了用sPn测定震源深度的可能性及该方法在日常工作中的应用问题。     

结构函数法反演气溶胶光学厚度中像元的间隔设置

结构函数法气溶胶光学厚度反演精度受像元间隔设置影响很大,且并非所有像元都能获得较好的反演结果,因而研究像元间隔的设置能够提高反演精度,研究反演误差小的像元能够提高算法效率。为了获得最佳的像元间隔设置,本文以胶州湾地区为例,利用250 m和500 m两种分辨率数据计算了不同像元间隔时的结构函数值,分别利用单一像元间隔法、均值法、坡高法以及线性区域均值法获得待反演像元最终的结构函数值反演550 nm处的气溶胶光学厚度,并依据CE318观测数据进行精度验证,通过分析点对点反演结果和光学厚度的空间分布,确定反演误差小、受分辨率影响小的像元间隔设置。实验发现线性区域均值法在一定程度上提高了反演精度和稳定性。此外,通过对反演结果可接受像元的地表反射率结构函数值的统计和分析,发现500 m分辨率时可接受像元比例优于250 m,当地表反射率结构函数值大于0.02时反演结果较好,而这些像元往往分布在山麓、山涧、海岸线、河流、城乡结合部等地理要素的突然改变的地区。     

地球内部应变与应力固体潮

本文详细介绍了地球内部应变和应力固体潮的计算理论,基于PREM地球模型计算了地球内部的Love数,并计算了地球内部的应力和应变的6个独立分量在不同深度和纬度处的时间变化序列.结果表明:应力潮汐的振幅达到10³Pa,应变潮汐振幅达到10^-8;不管应力或是应变潮汐,其振幅随深度的不同都有较大的变化;6个应力和应变分量对纬度依赖较大,但没有表现出南北纬度上的严格的对称性,与纬度的对应关系由引潮位展开的大地系数确定.本文结果可有效应用于地球内部应变或应力潮汐观测的固体潮改正;另外,将本文结果应用于研究潮汐触发地震问题,给出了中国中部地区的一个算例,结果表明地震断层正应力潮汐和应力张量第一不变量潮汐与发震时刻具有明显的相关性,而这种相关性并未在其他如剪切应力以及库伦破坏应力潮汐中表现出来.     

基于ASTER VNIR SWIR多光谱遥感数据识别与提取干旱地区岩性信息——以西南天山柯坪隆起东部为例

ASTER多光谱遥感数据目前可以用于岩石矿物资源信息的识别和提取。本研究尝试利用ASTER 可见光近红外（VNIR）和短波红外（SWIR）的多光谱遥感数据提取干旱地区的岩石与矿物信息。基于新疆天山西南缘柯坪隆起东部不同地层单元岩石的化学组成和矿物成份以及VNIR SWIR谱域光谱吸收特征的分析,我们采用相关吸收波段深度（RBD）和波段比值（BR）方法对研究区的多光谱遥感数据进行图像处理,有效区分和识别了白云岩、石灰岩、砂岩以及阿克苏群的蓝片岩—绿片岩和砂质片岩。白云岩的CO2-3吸收谱带中心波长位于232〖KG*3〗μm,与灰岩的CO2-3 吸收谱带中心波长位置235 μm相比,具有向短波长方向移动的特点,据此可以利用RBD7、RBD8分别有效的识别白云岩和灰岩; 长英质岩石显示Al OH和Fe3+ VNIR SWIR吸收特征,而基性 超基性岩石显示Fe2+ 和Fe、Mg OH特征,利用不同的铁价态和次要矿物可以区分它们：ASTER band2/band1代表了含Fe3+ 矿物分布信息、ASTER band5/band4代表了含Fe2+ 矿物分布信息、RBD6可以估计Al OH矿物的丰度; 砂质/泥质片岩含较多的多硅白云母、绿泥石、黑硬绿泥石以及风化后表面覆盖的其它粘土矿物,在221 μm（band 6）存在有特征的吸收谱带,并且在165 μm（band 4）具有较高的反射率,而蓝片/绿片岩在221 μm（band 6）反射率较高,不具有明显特征吸收谱带,同时其在165 μm（band 4）反射率较低,因此蓝片/绿片岩ASTER band4/band6 比值低。应用ASTER band4/band6波段比值可以有效的区分开砂质/泥质片岩与蓝片岩/绿片岩。     

关于成岩成矿深度构造校正测算的理论基础、方法和实例

成岩成矿深度的构造校正测算方法,是从测算压力中先消除掉构造附加静水压力之后再计算上覆岩石厚度,即成岩成矿深度的方法。该方法基于对地壳岩石处于固体应力状态的认识之上,采用弹性固体模型代替静止流体模型,对“上覆岩石重力在数值上等同于该点所承受的静水压力”这一通常的认识提出了不同见解,比沿袭至今单纯用压力/比重(或密度)方法得出深度更符合于实际情况。本文介绍了该方法的理论基础和野外地质研究方法——开展变形岩相形迹填图,在室内利用三维变形和古差应力测量,根据样品所处构造部位和性质,选择不同的参数换算成矿时差应力的众值。以胶东玲珑——焦家式金矿床为例,求得成矿深度仅3.5km或更浅,进而提出更深部位存在深部金矿富集带的预测意见。胶东几个大型金矿深部第二富集带已揭露的勘探资料证实这一认识比较符合实际情况。用这一方法测算出大别超高压带含柯石英榴辉岩形成深度仅32km多,而不是用压力/比重方法估算的100多公里,这为大别造山带的构造格局和演化历史的研究提出新的途径和方法。     

MODIS遥感中国近海气溶胶光学厚度的检验分析

基于中分辨率成像光谱仪(TERRA/MODIS)的一级数据和相应的辅助数据,利用MODIS/ARIS预处理软件包(IMAPP)中的气溶胶软件反演得到中国近海气溶胶的光学厚度,与AERONET太阳光度计的反演结果作对比分析,验证了此反演方法的可行性.研究了2002年10-11月中国近海气溶胶光学厚度和Angstrom指数(表征粒子谱宽度)的变化特征,进一步结合气块后向轨迹分析和地理环境背景场信息讨论了卫星反演气溶胶光学参量的适用范围和误差来源,结果表明:IMAPP反演得到的气溶胶光学厚度,在东海和日本以南等广阔海域与气溶胶地基观测网(AERONET)的观测结果基本一致;在渤海和黄海近海岸一带反演值偏高,其主要原因是该海域存在二类水体的影响.     

The Present Status and Prospect of Earthquake Focal Depth Locating

Locating an earthquakes focal depth is always a key project in seismology. Precise focal depth is of critical importance for evaluating seismic hazards, deciphering dynamic mechanisms of earthquake generating,estimating aftershock evolutions and risk,as well as monitoring nuclear tests. However,how we determine an accurate focal depth is always a challenge in seismological studies. Aiming to solve these problems, we analyzed and summarized the present status and the future development of earthquake focal depth locating. In this paper we first reviewed the present status of focal depth locating in the world,and summarized the frequently-used relocating methods and ideas at present,and introduced two types of focal depth relocating ideas: arrival time relocating and waveform modeling methods. For these ideas,we systematically described the S-P and the Pn-Pg methods that belong to arrival time method,and polarization focal depth locating and amplitude focal depth locating that belongs to waveform modeling,and further analyzed the advantages and limitations of these methods. Since the depth phase methods are highly sensitive to focal depth,and are relatively free from the uncertainties of crustal models,we mainly reviewed the depth phases of s Pm P,s PL,s Pn,and s Sn,and quantitatively evaluated their availabilities and characteristics. Second,we also discussed the effects of crustal velocity models on the reliability of focal depth locating,and reviewed the advancements of seismic tomography techniques over recent years. Finally,based on the present status of the progress on the focal depth locating,and studies of seismic velocity structures,we proposed an idea of combining multiple datasets and relocating methods,jointly utilizing seismologic and geodetic techniques to relocate focal depth,which should be the major research field in investigating focal depth and source parameters in the near future.     

基于MODIS数据的新疆大气气溶胶光学厚度时空变化分析

利用中分辨率成像光谱仪（Moderate-resolution Imaging Spectroradiometer,MODIS）大气气溶胶光学厚度产品数据，采用三角剖分算法、最近邻点搜索、插值法和趋势分析法，分析新疆气溶胶光学厚度（Aerosol Optical Depth,AOD）时空变化。结果表明：（1）新疆AOD总体呈下降趋势且地域差异明显，南疆AOD明显高于北疆，高值区主要集中在塔里木盆地边缘和天山北坡经济带。（2）北疆AOD年际变化不明显。2014年最高，2005年最低，年均值在0.15～0.18。南疆则呈明显的年际变化。最高值出现在2006年，为0.42；最低值出现在2017年，为0.22。（3）新疆AOD呈明显季节变化特征。春季最大，秋季最小。（4）2003—2019年南疆环塔里木盆地北部、东南边缘和北疆沿天山北坡经济带AOD增量明显。