First data on the coastal dynamics and the sedimentary characteristics of the area influenced by the River Irminio basin (SE Sicily)

The various lithological outcrops in the drainage basin of the River Irminio are described for their contribution to the riverborne material and therefore to the sedimentary balance of the coastal strip. The main contribution to the present sedimentary balance of the subaqueous delta cannot be attributed to the River Irminio, owing to the extreme difference between fluvial and marine sediments. The river's hydraulic characteristics have not always been constant but have tended to decrease in three stages: the first, with a strong competence, shown by the Quaternary alluvial sediments with pebbles; the second, up to 1985, of medium competence, shown by sandy-gravelly deposits in the coastal strip and by finer sediments in the distal areas; the third, at the present day, with low competence, shown by a prevalently suspended load sediment with practically no fluvial influence and with a sedimentation dominated by the littoral currents; this is because between the 1960s and 1970s, owing to interventions along the river channel, the sediments from the basin were reduced to the point of non-existence and a new sedimentary cycle was set up on the delta with allochthonous sediments, exclusively made up of quartz clasts, whereas in the distal zones the mineralogical and compositional characteristics of the ancient river mouth were maintained.     

罗布泊“湖心”位置的探讨

罗布泊是我国干旱地区著名的湖泊,地处古代沟通东西文化的通道—丝绸之路的要冲,在我国古代史上享有盛名,是一个充满自然和文化之谜的神秘地区。通过对罗布泊地区高程测量数据的分析,确定其湖心的具体位置。罗布泊＂大耳朵＂纹理目前被认为是罗布泊湖水退缩留下的印迹,从沉积学角度考虑,罗布泊的湖心应处在耳心处。2006年DGPS实测结果表明罗布泊最低点处于＂大耳朵＂的耳心处（90.500°E、40.131°N）。研究罗布泊的＂湖心＂位置确定对科考、科研、旅游和文化等有较高的价值。     

不同管理方式对参池颗粒物质沉降作用及沉积物的影响

为探究不同管理方式对刺参养殖池塘(简称参池)沉降颗粒物及相关底泥、水体指标的影响,分别测定9口参池(分为养水机、自然纳潮、微孔曝气3组参池,每组3个重复)颗粒物质在四季的平均沉降量和水平空间分布情况,底泥有机质含量和弧菌(Vibrio)总数,水体营养盐含量、浮游植物生物量和净初级生产力。结果显示,自然纳潮和微孔曝气池塘颗粒物质平均沉降量的季节、水平分布均无显著差异(P>0.05);养水机池塘颗粒物质平均沉降量在夏季为(30.33±2.46) g/(m2?d),极显著高于另外2组参池(P<0.01),在冬季为(7.49±1.17) g/(m2?d),显著低于另外2组参池(P<0.05);在水平分布上,养水机池塘沉降颗粒物的分布较另外2组参池更均匀;在相同季节,养水机池塘底泥有机质含量和弧菌总数均处于3组参池的最低水平,微孔曝气池塘总体次之,自然纳潮池塘总体最高;3组参池的水体营养盐含量接近,而养水机池塘浮游植物生物量、净初级生产力均处于3组参池中最高水平,微孔曝气池塘总体次之,自然纳潮池塘总体最低。本研究表明,传统海参养殖在自然纳潮换水管理基础上,辅助适宜设备能够影响颗粒物质的沉降规律,加快参池底泥–水体之间营养物质交换,改善水底养殖环境。     

The mangrove communities in the Arroyo Seco deltaic fan,Jalisco, Mexico,and their relation with the geomorphic and physical–geographic zonation

This work investigates mangrove tree zonation dynamics in a deltaic fan in the southwestern coast of Mexico. A hypothetical evolution that led to the formation and consolidation of the Arroyo Seco deltaic fan based on the environmental components from the hydrographic basin is proposed. Also, the relief morphogenetic types, along with their sedimentary composition, are derived from geomorphologic and edaphic diagnose methods. Finally, mangrove tree zonation, basal area and height along transects traced parallel to the relief are related to morphogenetic types and to the water table depth during the dry period. There was a clear sedimentological evidence of the accretion process in the deltaic fan. The accretion horizons conditioned the water table, which increased in depth from the margin of the lagoon to the hinterland, thus changing among geoforms. It was much greater at the middle part of the transects, where continental or lagoon water did not infiltrate due to high resistance of clayey soils. The geomorphic zonation of mangrove communities in the Arroyo Seco deltaic fan is: (1) a low fluvial distributary accumulative plain, with coconut palm plantations; (2) a bank fluvial accumulative plain between distributary channels, with coconut palm plantations and patches of low tropical forest; (3) a relatively high swamp accumulative plain, flooded during high water levels, with Avicennia germinans; (4) a low swamp, temporarily flooded accumulative plain, with Rhizophora mangle, Laguncularia racemosa and A. germinans; (5) a very low swamp, permanently flooded accumulative plain, with distributary channels, lateral microbars and tide microdepressions, where Rhizophora and Laguncularia codominate; and (6), a Rhizophora fringe and colonization area along the fan's frontal edge on the same plain. Along this gradient composed of six mangrove communities, basal area and height tended to increase as the water table reached soil level.     

Lithological factors affecting magnetic susceptibility of subtropical soils, Zhejiang Province, China

Magnetic susceptibility (χ) was measured on subtropical soils formed on a range of parent materials in Zhejiang Province, China, to demonstrate the influence of parent material lithologies on the amount and vertical distribution of χ in the soils. We found that the χ values of soils vary by up to two orders of magnitude with their parent material lithologies. Soils formed on igneous rocks with high χ values showed high absolute χ and distinctly decreased χ compared with χ values of parent materials. The χ values of soils formed on basalt, andesite and granodiorite were >250×10⁻⁸ m³ kg⁻¹. The χ values of soils formed on granite, and other neutral and acid igneous rocks ranged from 50×10⁻⁸ to 120×10⁻⁸ m³ kg⁻¹. In most of the soils formed on sedimentary rocks, χ enhancement in upper horizons of soils was found compared with parent material χ. This enhancement was believed to be pedogenic formation of superparamagnetic (SP)–stable single domain (SSD) magnetic grains, which are characterized by high values of frequency dependent susceptibility (χ_fd) and anhysteretic remanent magnetization (ARM). Soils formed on sedimentary rocks with a very low initial χ and iron content showed a low χ value throughout the profile. It was found that there is a highly significant relationship between the χ values of soils and their dithionite–citrate–bicarbonate solution (DCB) soluble iron contents (Fe_d). The χ values of soils in chronosequences formed on alluvium and two marine deposits increased as soils became older. It is suggested that the χ values can be used as a tool for determining the relative age in chronosequence studies.     

桑沟湾贝类养殖区沉积碳库年汇入速率的高分辨率记录及其对人类养殖活动的响应

本研究对2014年取自桑沟湾贝类养殖区的柱状沉积物进行分析,测定每层沉积物中总碳(TC)、总有机碳(TOC)和总氮(TN)的质量分数,并计算总无机碳(TIC)、海源性有机碳(Cm)和贝壳无机碳(Shell-IC)的质量分数以及各组分碳在总碳中的贡献率,同时对其年汇入速率(BF)进行估算。结合210Pb测年法,研究近80年沉积碳库各种碳的年汇入速率的高分辨率记录,发现其中TC、TIC、TOC、Cm和Shell-IC的平均含量分别为1.09%、0.75%、0.34%、0.15%和0.06%。研究还发现,TIC是TC的主要形式,在1960—2010年的贡献率保持在60%以上。Cm的质量分数在2010年前无较大幅度的波动,但在2010年后显著增加,使得Cm/TC及TOC/TC也显著提升。Shell-IC在养殖活动开始后至2000年一直处于较低水平。各组分碳的年汇入速率在1960—2000年间随海水养殖活动呈现相应的变化,之后由于养殖规模和格局的调整,BFCm、BFTOC和BFTC显著升高,BFTIC降低,BFShell-IC先升高后降低。桑沟湾的海水养殖活动影响着贝类养殖区沉积碳库的组成和年汇入速率,碳库各组分的变动也体现出与之相应的变化。本研究详细描述了人类海水养殖活动在开始后的50年里对沉积碳库年汇入速率的影响特征,也为今后陆架海区水产养殖活动的合理规划提供参考。     

基于多Agent社会模型在油田储层沉积相研究中的应用

为了建立储层沉积相分析的复杂地质模型,将多Agent技术和面向Agent的软件工程技术引入到储层沉积相分析中,在地质储层沉积相分析的基础上,建立了基于多Agent的储层沉积相分析模型.对面向Agent混合智能的Gaia方法论进行了研究,具体步骤分为收集需求信息、分析阶段、框架设计阶段、详细的设计阶段和实现阶段,逐步完善沉积相分析的模型建立.并在此方法论的基础上设计了沉积相分析的Agent模型、角色模型、技巧模型、知识模型和组织模型、交互模型.最后,构建了一个基于多Agent储层沉积相分析社会模型的原型系统,验证了系统的有效性.     

中国中亚热带网纹红土的地球化学特征与沉积环境

130个样品的粒度、黏土矿物组成、地球化学特征以及Sr、Nd同位素分析表明,广泛分布在中亚热带地区并且具有一定厚度的第四纪网纹红土为加积型沉积。该类沉积粒度组成与北方风尘沉积类似,粉砂含量占优势,>50μm含量小于5%,5~50μm组分41.2%~61.5%,<5μm黏粒26.9%~55.8%;黏土矿物组成中含有较多的石英、云母和高岭石;全土体的平均硅铝率为7.96,硅铁铝率6.11;稀土元素丰度179.6 mg kg-1,与地壳平均值(178 mg kg-1)、北京郊区1998年12月大气粉尘稀土总量(178.0 mg kg-1)以及两块中国黄土标样(178.2mg kg-1)非常接近,并且表现为轻稀土强烈富集,重稀土淋失,Ce元素正异常;网纹红土全岩样品的87Sr/86Sr值界于0.725 657~0.727 714之间,Nd同位素0.511 989~0.512 098,与佳县上新世红黏土和黄土的酸不溶相性物质接近。理化特征指示,第四纪加积型网纹红土与北方黄土中的古土壤以及上新世红黏土的形成环境类似,并且具有稳定的物质来源。