三叠纪嘉陵江期华蓥山同沉积断层的沉积、储层响应

对于断裂带在地质历史时期活动特点的认识,因多期次、不同活动性质的叠加改造而难以确定。以四川盆地南部嘉陵江组为例,通过三叠纪嘉陵江期华蓥山断裂带两侧的沉积、储层的研究发现沉积、储层响应与断面倾向南东、东侧下降的观点矛盾。主要表现为:在非浅滩化的嘉三期,紧邻断裂带西北侧的下降盘地层异常增厚;浅滩化的嘉一晚期—嘉二1期,东南侧的泸州古隆起地区颗粒岩累计厚度较西北侧增厚;另外,断层东南侧的颗粒岩发育早期岩溶型储层,而在西北侧这类储层欠发育。结果表明在三叠纪嘉陵江期华蓥山断裂带的断面倾向北西,为西侧下降的同沉积正断层。     

蜀南地区飞仙关组高精度层序地层研究

针对四川盆地下三叠统飞仙关组层序地层存在多种不同划分方案,以高精度层序地层学理论与方法为指导,以蜀南地区飞仙关组台地相碎屑岩和碳酸盐岩为研究对象,以野外露头剖面、岩芯、钻井、测井、地震等资料为基础,综合应用岩性突变面、沉积相转换面、沉积物空间堆积样式的变化、早期成岩变化、电测井曲线特征以及地震反射特征等标志,识别出不同级次的11个层序界面,据此将本区飞仙关组划分为2个三级层序(TSQ1和TSQ2)和10个四级层序,其中TSQ1可细分出6个四级层序,TSQ2可再分出4个四级层序,并将其与传统地层单位进行对比:三级层序TSQ1和TSQ2分别对应于飞一段+飞二段地层和飞三段+飞四段地层。通过层序地层对比和层序地层格架的建立,指出这些层序在全区均具有良好的可对比性和等时性,每个层序均具有快速海侵到缓慢海退的特点,均由海侵体系域和高位体系域构成,未发现低位体系域和凝缩段。层序与储层关系的研究表明,四级层序Ⅲ和Ⅷ是台内鲕滩这种有利储集相带的主要发育层位,所形成的滩相鲕粒灰岩储层与高位体系域的向上变浅序列和早期暴露及其所导致的大气淡水淋溶改造有关,平面上集中分布于中东部地区。     

People’s perception and socioeconomic determinants of soil erosion:A case study of Samanalawewa watershed,Sri Lanka

Though soil erosion is an important concern in Sri Lanka, there is a dearth of baseline information on soil erosion in many ofits watersheds, which obstructs monitoring of soil erosion and mitigating its effects. In order to assess soil erosion in a critical watershed and to identify its determinants, the Samanalawewa watershed, which contains one of the main hydropower generating reservoirs in Sri Lanka, was selected for this study. Remote-sensing (RS) and geographic information system (GIS) based modeling...     

Dredging influenced sediment toxicity of endosulfan and lindane on black tiger shrimp （Penaeus monodon Fabricius） in Chantaburi River estuary in Thailand

Series of experiments, including background sediment elutriate, spiked-sediment elutriate and spiked- water toxicity tests, were carried out to study the effect of dredging on survivability and ecological competence of commercially important shrimp postlarvae of Penaeus monodon Fabricius. The test sediment represented the most contaminated from endosulfan and lindane in the Chantaburi river mouth estuary. The maximum sediment contamination levels were 49.4 μg/kg of endosulfan and 58.1 μg/kg of lindane in dry weight basis. Dose-response studies in static, non-renewal spiked-sediment elutriate toxicity tests revealed that LC 50 （96 h） values for survival effect based on measured concentrations were 0.50 （0.26-0.95） μg/L for endosulfan and 0.92 （0.63-1.34） μg/L for lindane. The LOECs for endosulfan and lindane were 0.141 and 0.429 μg/L, respectively. The NOECs were estimated to be the dissoluted endosulfan and lindane concentrations from the Chantaburi estuary sediment. The effects on phenoloxidase enzyme activity in shrimp postlarvae exposed for sub-lethal to lethal doses in sediment elutriate were not significant （p〉0.05） at all tested dose levels. The worst case dissolution concentrations of endosulfan and lindane in the water column upon simulatory dredging in the Chantaburi estuary were found to be toxic to shrimp postlarvae on lethal and sub-lethal effects. The NOECs of respective chemicals （i.e., 0.034 and 0.16 μg/L） shared the same orders of magnitude for corresponding NOECs established for whole salt water aquatic life by the USEPA and ＂safe＂ levels calculated by 0.01 safety factor approach. In addition, the significance of multiple pollutant assessments for ecological toxicity testing is highlighted.     

泰国北部难河构造带二叠纪放射虫、硅质岩和玄武岩

在泰国北部难河构造带Pha Som变质杂岩中发现保存很好的放射虫硅质岩、玄武岩地层层序.层状硅质岩含放射虫化石Follicucullus porrectus, 地质时代为中二叠世晚期至晚二叠世早期.其硅质岩SiO₂含量均在92.5%以上, Al/ (Al+Fe+Mn) 平均比值为0.51, Ce/Ce*比值为1.14, 为大陆边缘型硅质岩.玄武岩具有富集大离子亲石元素与高场强元素以及轻稀土富集等洋岛玄武岩的特点.说明难河构造带中-晚二叠世之交存在洋岛型火山岩和靠近大陆边缘的深海盆地硅质岩, 代表了小洋盆的沉积组合.该构造带闭合时间应在晚二叠世与晚三叠世之间.