东昆仑中泥盆世A型花岗岩的确定及其构造意义

东昆仑中泥盆世冰沟正长花岗岩具有高硅(SiO₂含量为71.85%~72.77%)和高碱(K₂O+Na₂O值为8.39~8.58)、相对富铝(A/CNK为0.93~1.03)、高FeO_t/MgO(6.24~7.86)和104 Ga/Al值(3.04~3.60)、富集轻稀土、明显的Eu负异常、相对原始地幔明显富集Zr、Ga、Y和Hf等高场强元素并强烈亏损Ba、Sr、P和Ti元素的特征, 这些特征与A型花岗岩类的地球化学特征一致.采用锆石LA-ICP-MS U-Pb法获得206Pb/238U值加权平均年龄为391±3 Ma(MSWD值为2.36), 表明该岩体为中泥盆世岩浆活动的产物.综合全岩Sr-Nd同位素、地球化学及实验岩石学等资料, 可以判断该岩石为造山后伸展阶段长英质地壳物质(变杂砂岩)在低压高温氧化条件下发生部分熔融的产物.冰沟正长花岗岩是目前东昆仑地区报道的时代最晚的古生代A型花岗岩, 它的出现可能标志着中泥盆世时期东昆仑始特提斯构造演化的彻底终结和古特提斯构造演化的崭新开始.      

Using data‐driven methods to explore the predictability of surface soil moisture with FLUXNET site data

Soil moisture (SM) is a key variable of land surface‐atmosphere interactions. Data‐driven methods have been used to predict SM, but the predictability of SM has not been well evaluated. This study investigated what variables and methods can be used to better predict SM for leading times of 7 days or longer with a global coverage of FLUXNET site data for the first time. Three machine‐learning models, that is, Bayesian linear regression, random forest, and gradient boosting regression tree, are used for the prediction. Variables including atmospheric forcing, surface soil temperature, time variables (year, day of year, and hour), the Fourier transformation of time variables, and lagged SM (7‐ to 14‐day lagged) were sequentially added into models. A framework with five experiments is designed for factorial exploration of SM predictability. A stepwise method was used to build the best models for each site. The performance of regression models became better when adding more explaining variables in most cases. The results showed that from 50 to 95% of variation of the best models can be explained. The important explaining variables are lagged surface SM, followed by day of year, year, soil temperature, and atmospheric forcing. The predictability of SM depends highly on SM memory characteristics and the persistence of seasonality. The effect of SM memory characteristics on SM prediction as an initial condition question has been widely discussed in this paper. Our results also provide an insight that mechanisms of seasonality effects on SM should be also paid more attention to.     

Studies on rickettsia-like organism(RLO)disease of tropical marine pearl oyster--Epidemiologicai investigation of RLO disease in juvenile populations of maricultured Pinctada maxima

The death which occurred in juvenile population was a severe problem in the course ofPinctada maxima artificial culture. With the methods of field investigation, histological study andstatistic analyses, the epidemiological study was carried out on the disease and death in juvenile popula-tions of Pinctada maxima in the Xinying Pearl Oyster Mariculture Farm of Lingao County (for the A,B and C batches of cultured juveniles hanged in the sea) and the Xincun Pearl Oyster Mariculture Farmof Lingshui County (for the D batch of cultured juvenile hanged in the pond), Hainan Province fromNovember 1993 to April 1995. The results show that the deaths which occurred in juvenile populations of Pinctada maxima pre-sented an outbreak pattern. The peak of mortality rates, in general, occurred in 4-to 6-month old pearloyster juveniles, and the mortality rates gradully declined with the extention of pearl oyster age after cul-turing 8 months. The correlation between the mortality rates of juvenile populations and mean bodylengths of juvenile populations show that the mortality rate become higher under 4 cm of mean bodylengths of juvenile population and become obvious declined over 5 cm of mean body lengths. The peak ofmortality rate occurred in 1 ～3 cm of mean body lengths. The results of histological observation showedthat rickettsia-like organism inclusions were common, histological widespread infective agent among ev-ery batches (A, B, C and D) of cultured juvenile populations. The mean severity indices (SI) of rick-ettsia-like organism (RLO) infection were positively correlated with mortality rates of juvenile popula-tions. After or within every peaks of RLO infection were all accompanied with the peaks of mortalityrates of host populations and the mortality rates declined with decreased RLO infection. So the evidencesof histological observation and epidemiology in this study indicated that rickettsia-like organism (RLO)may be as an important pathogenic organism of disease and death of cultured Pinctada maxima. In addi-tion, a few ciliates were discovered only in part of batch A of cultured juvenile population. The mortalityrates in juvenile populations were not correlated with the weekly mean temperature and salinity of seawater.     

应用P—S曲线分析非线弹性地基上的欧拉——伯努利梁

在较大外荷载下,搁置在地基上的Bernoulli—Euler梁下部的土体会发生塑性变形。在使用有限差分法离散了文克勒地基梁（Winkler）的控制方程后,形成了线性代数方程组,然后调用计算机Fortran程序进行了求解。利用p-s曲线,通过迭代,使用有限差分法求解了考虑土体塑性的变基床系数的Winkler地基梁的位移。计算结果表明：通过p-s曲线和变基床系数的Winkler地基梁模型,可近似分析出地基在外荷载作用下是进入弹性阶段还是弹塑性阶段,并给出较为合适的地基沉降值。最后,讨论了算法的应用范围。     

Mechanism of sinkhole formation during groundwater-level recovery in karst mining area,Dachengqiao, Hunan province,China

The Meitanba Coal Mine area in Hunan province, China, had been impacted by severe cover collapse sinkholes since 1982 due to mine dewatering. After the coal mine was closed in February 2015, the groundwater level has increased significantly. A series of sinkholes were recorded in the study area during groundwater-level recovery. Analysis of monitoring results and in-situ investigation indicated that 13 sinkhole collapses were more likely induced by abrupt change of groundwater–air pressure in response to heavy rainfall from March 2015 to July 2016 when the groundwater level increased by as much as 76 m. When the karst conduit was flooded, a relatively sealed environment was formed between saturated sediments and flooded karst conduit. Implosion of entrapped air might have caused the cave roof to collapse followed by surface collapses in a short time. On the other hand, four sinkholes occurred in November 2016 when the groundwater levels were near the soil–bedrock interface at elevations between 52.5 and 58.9 m amsl and the groundwater-level increase was at slower paces. Field measurements indicate that the groundwater-level fluctuation at the soil–bedrock interface could enlarge the soil cavity and accelerate the subsoil erosion process.     

基于小波包变换的重叠地震波分离

利用dmey小波包变换提取时频特征,采用阈值熵搜索最优小波包基方法,用Matlab语言编程,实现对重叠地震信号的分离.通过对2009年2月20日柯坪M5.2地震波和其后ML4.7余震的研究,发现用该方法能清楚地找到同源地震重叠的位置,为地震定位提供准确、可靠的震相识别依据,从而提高地震定位的精度.     

地震勘探方法在赵官井田岩浆岩解释中的应用

赵官井田位于山东省的西北部,该区岩浆岩较发育,有三层岩浆岩呈岩床状侵入到煤系地层中。下层岩浆岩一般位于10煤以下,但在井田局部区域,也会上冲至10煤层,甚至达到7煤层,造成冲断条带两侧煤层底板形态发生剧烈变化,10煤或7煤直接吞蚀。依据赵官井田岩浆岩的发育规律及煤岩性特征,利用三维地震勘探方法查明了井田内三层岩浆岩的赋存状态,尤其对下层岩浆侵入形态以及对煤层的影响进行了解释,否定了以往地质资料中因岩浆侵入煤层而误解释为多条逆断层的存在。赵官庄井田三维地震勘探实例表明,岩浆岩冲断煤层在时间剖面上具有典型的响应特征,并指出下层岩浆岩的上冲的影响井田浅部煤层开采的一个重要地质因素。     

县级海域生态环境质量评价技术方法研究 ——以普陀区海域为例

文章构建了县级海域生态环境质量评价指标体系,建立了县级海域环境质量系数计算模型、县级海域生态质量系数计算模型以及县级海域生态环境质量综合评价模型,定义了县级海域生态环境质量评价流程。以普陀区海域为例,对县级海域生态环境质量进行综合评价,并针对关键问题和主要影响因素,提出实而可行的合理化建议,以及改善县级海域生态环境质量的长效机制。     

Cloning and characterization of a delta-6 desaturase encoding gene from Nannochloropsis oculata

A gene(NANOC-D6D) encoding a desaturase that removes two hydrogen atoms from fatty acids at delta 6 position was isolated from a cDNA library of Nannochloropsis oculata(Droop) D.J.Hibberd(Eustigmatophyceae).The unicellular marine microalga N.oculata synthesizes rich long chain polyunsaturated fatty acids(LCPUFAs),including eicosapentaenoic acid(20:5n-3,EPA).The deduced protein contains 474 amino acids that fold into 4 trans-membrane domains.The neighbor-joining phylogenetic tree indicates that NANOC-D6D is ...     

瞬态瑞雷波探测技术及其在矿井地质中的应用

稳态瑞雷波勘探是由高到低逐渐改变振动频率的瑞雷波勘探方法,而瞬志瑞雷波勘探是宽频谱瑞雷波勘探。本文重点介绍了瞬态瑞雷波勘探原理、数字处理技术及其在矿井地质勘探中的应用。