中国九龙江河口营养盐基准值研究

One of the key concerns in estuarine and coastal environments is eutrophication, which is known to be closely connected to nutrient enrichment. To control and improve surface water quality, nutrient criteria are recommended in order to provide reference conditions for the environment. However, the current datasets of nutrient criteria in China are either designed for surface water or sea water, and as such these are not suitable for assessing estuarine water quality, especially given the unique ecosystem and dynamic properties of estuaries. To address this issue in current estuarine water management, nutrient criteria have been developed for a local estuary in the southeast of China. Segmentation of the Jiulong River Estuary, China was firstly analysed through field investigations carried out during 2013–2014, which resulted in the delineation of three segments characterized by their distinct properties in relation to salinity, hydrology, ecosystems, etc. Historical records from 1997 to 2014 were then analysed using statistical modelling to develop candidate nutrient criteria for the estuary.This stage of the analysis was undertaken in combination with the study of nutrient status records from the 1980s,which were used to establish a baseline reference condition. The recommended criteria values of dissolved inorganic nitrogen(DIN) in Segments Ⅰ, Ⅱ and Ⅲ of the Jiulong River Estuary are 64, 21 and 14 μmol/L,respectively, and the corresponding values for soluble reactive phosphorus(SRP) are 0.89, 0.76 and 0.89 μmol/L,respectively. It should be emphasised that these values are site-dependent, and that different results may be achieved at other locations depending on the physical and biogeochemical characteristics of an estuary, or even a single site within a catchment. It is hoped that by demonstrating a possible methodological approach and methods of nutrient criteria derivation in the Jiulong River Estuary, the current study will offer researchers some fundamental basis from which to begin to develop more complete nutrient criteria indices for the study of nutrient conditions in other estuaries throughout China.     

桂西北南丹-荔波地区中、新生代构造演化:来自古构造应力场的证据

桂西北南丹-荔波地区是我国重要的锡多金属矿床富集地,近年来油气勘探显示该区亦具有极大的海相页岩气成藏潜力。因此,深入探讨和认识该区中、新生代构造应力场特征及其构造演化是成矿规律研究和页岩气勘探过程中不可或缺的重要环节。本文以南丹-荔波地区广泛发育的褶皱、共轭节理和断层为研究对象,在详细野外观测的基础上,利用叠加褶皱、共轭节理分析以及断层滑动矢量等方法,反演了研究区中、新生代构造应力场变化。构造解析表明,该区中、新生代共经历了四期构造应力场的交替和演化,分别为NNE-SSW 向挤压、NW-SE 向挤压、NEE-SWW 向伸展和近E-W 向挤压。结合区域构造演化特征,推测NNE-SSW 向挤压应力场的形成可能与印支期华南大陆南北边缘与印支/华北板块碰撞闭合有关;NW-SE 向挤压应力场和NEE-SWW 向伸展应力场可能分别对应于燕山早期古太平洋板块向华南大陆之下的俯冲消减以及燕山晚期发生的弧后伸展作用;近E-W 向挤压应力场可能形成于喜山期印度?欧亚板块陆陆碰撞所产生远程效应的构造背景之下。     

利用人工神经网络方法对牙形石鉴定中若干“模糊特征”的数字化研究

牙形石是一类在地层学研究中具有重要意义的古生物化石。但由于牙形石鉴定中存在诸多重要、却难以定量分析的“模糊特征”,使得牙形石的鉴定和分类工作长期依赖于古生物工作者的经验。利用数学中的非线性方程将这些“模糊特征”进行数学描述,并利用人工神经网络中的反向传播算法设计出一套多隐含层的前馈网络分类器,对这些“模糊特征”进行分类尝试,取得了良好的效果,为牙形石的进一步数值化研究奠定了基础。     

新疆乌伦古河地区铀矿化类型及其特征

新疆东北部乌伦古河地区位于天山-兴蒙造山系东-西准噶尔弧盆系,涵盖准噶尔洋内弧（萨吾尔山-加波萨尔岛弧）、科克森他乌-阿尔曼泰蛇绿岩混杂岩带、塔尔巴哈台-三塘湖复合岛弧带（卡拉麦里-莫钦乌拉岛弧带）等3个Ⅲ级构造单元（潘桂棠等,2009）,属哈萨克斯坦波谢库尔-成吉斯到我国雪米斯坦-沙尔布提Cu-Au-Be-U成矿带（申萍等,2015）的东延,相邻的雪米斯坦山地区已发现有白杨河铍铀矿床等一系列的铀矿床、矿点和矿化点,乌伦古河地区虽未发现成规模的铀矿床和铀矿点,但已发现大量的铀矿化点和异常点,具有较大的铀成矿潜力。根据其铀矿化赋存主岩、矿化特征及控制因素,乌伦古河地区铀矿化类型主要见碳硅泥岩型、伟晶岩型、花岗岩型和表生富集型,其中以碳硅泥岩型铀矿化为主。     

渤海湾盆地惠民凹陷临商断层特征及其活动机制

临商断层为济阳坳陷惠民凹陷内部NE向展布的控洼断层之一,详细地分析这些断层的活动性对于深入了解古近系沙河街组沙三段开始沉积以来惠民凹陷的差异分化具有重要的意义。本文通过详细解剖临商断层的几何学特征,不同时期、位置的断层活动性,并结合新生代以来渤海湾盆地的构造演化,得出以下认识:①临商断层的雏形为一右旋走滑正断层。②断层的主枝由西往东活动速率逐渐增强,而分枝断层则表现为中间强、两侧弱。③时间上的差异性表现为古近系沙河街组沙三段沉积期—古近系沙河街组沙二段沉积期断层的活动性较强,在古近系沙河街组沙二段沉积期达到最高值,而后逐渐减弱,古近系东营组沉积期出现小规模的增强,新近系馆陶组沉积期断层活动性达到最低值,新近系明化镇组沉积期断层活动性开始增强。④空间上断层活动的差异主要是由于该断层走滑过程中形成的同向走滑断层的位置造成的,而时间上的差异性与渤海湾盆地新生代的构造演化具有较好的一致性。     

青东凹陷新生代垂向地层序列及展布特征

针对青东凹陷勘探程度较低、新生代地层发育特征尚不明晰的现状,从岩性、测井、地震、古生物化石等资料入手,结合区域地质背景,对凹陷新生代地层进行了构造层和岩石地层的多重划分,将其划分为古近系和新近系—第四系两个构造层,其中古近系构造层自下而上发育孔店组、沙四段、沙三段、沙二段,地层发育特征与东营凹陷相似,但垂向序列不完整,缺失沙一段和东营组。在此基础上结合钻井标定和地震剖面的解释,重点绘制了古近系四个构造亚层的残留地层等厚图,并对其展布特征进行了分析。结果表明,各构造亚层残留地层在厚度和展布方向上变化较大,且具有一定的规律性,体现了不同地质时期盆地沉积充填和构造演化的差异性。最后对青东凹陷缺失沙一段—东营组的可能原因进行了初步讨论,认为新生代地幔柱高点由渤海湾盆地南部迁移到渤海海域可能造成该地区在古近纪末期未接受沉积,而据垦东地区北部的物源在沙一—东营期来自南部也可推测该时期青东凹陷已抬升遭受剥蚀。