珠江三角洲第四纪沉积物TiO_2/Al_2O_3值及其地质意义

本文根据珠江三角洲第四纪沉积物TiO_2和Al_2O_3的化学分析资料,探讨了该地区TiO_2/Al_2O_3值及其地质意义。结果表明,珠江三角洲表层样品TiO_3从河道、河口向外海逐渐减小,其TiO_2平均值为:三角洲平原1.517,三角洲前缘1.201,潮汐河口湾1.001,浅海内陆架0.834.珠江三角洲钻孔岩芯样TiO_2值与沉积时间(7500a以来)呈正相关关系,并且TiO_2值逐渐增加;这种增加极可能是反映了珠江三角洲的延伸进积作用和河流作用的加剧。     

ENSO现象与台湾海峡西部海区中下层鱼类渔获量关系

对台湾海峡西部海区中下层多年（1956－1973年）渔获量变化与EN现象关系并结合捕捞强度进行一些初步分析，总结出渔获量变化规律，为合理开发渔业资源提供有用信息。     

热带西太平洋海温异常对大气影响的数值模拟

用IAP-GCM二层楼式,模拟1月份西太平洋暖池区海温增暖对1-8月份大气环流的影响,初步探讨暖池区海温异常对我国夏季降水的影响过程。指出北半球500hPa环流场对暖地区1月份海温增暖的响应存在着PNA和EAP波列,在冬季较为明显。其能量传播特征表示为南北半球的中纬度地区基本上是向东传播,在热带低纬度地区存在着准2个月的低频振荡。     

黄河三角洲下三角洲平原沉积环境

现代黄河三角洲活动叶瓣上河口附近发育着决口扇沉积物,潮汐影响不明显。两侧发育着具有进积潮滩特点的沉积物。叶瓣废弃后由于压实下沉和波浪作用海岸后退,形成退积潮滩。在废弃河口侧部发育较好。那里高潮线处没有侵蚀陡坎,海岸后退是由于压实下沉引起的。废弃河口附近侵蚀作用明显,高潮线处发育侵蚀陡坎,潮间带变窄。     

中西太平洋金枪鱼围网技术及存在的问题

金枪鱼围网产量约占全球金枪鱼捕获量的70%,发展金枪鱼围网渔业具有广阔的前景.本文根据中鲁远洋渔业股份有限公司金枪鱼围网渔船的作业情况,分析了围网作业中的一些捕捞技术,并探讨了在发展该项目中存在的问题.     

厦门西港表层沉积物中DDTs，HCHs和PCBs的含量与分布

对厦门西港表层沉积物中有机氯农药和多氯联苯的含量与分布进行调查研究。含量范围：ＨＣＨｓ为０．１４－１．１２ｎｇ·ｇ（－１），ＤＤＴｓ４．４５３１１ｎｇ·ｇ（－１），ＰＣＢｓ０．０５—７．２４ｎｇ·ｇ（－１）。与香港维多利亚港表层沉积物含量进行比较，厦门西港表层沉积物的ＰＣＢＳ含量低于维多利亚港，ＤＤＴｓ含量则高于维多利亚港。     

Seismic and sequence stratigraphy of the central western continental margin of India: late-Quaternary evolution

Seismic and sequence stratigraphic architecture of the central western continental margin of India (between Coondapur and south of Mangalore) has been investigated with shallow seismic data. Seismic stratigraphic analysis defined nine seismic units, that are configured in a major type-1 depositional sequence possibly related to fourth-order eustatic sea-level changes, comprising regressive, lowstand, transgressive and highstand systems tracts. The late-Quaternary evolution of the continental margin took place under the influence of an asymmetric relative fourth-order sea-level cycle punctuated by higher frequency cycles. These cycles of minor order were characterised by rapid sea-level rises and gradual sea-level falls that generated depositional sequences spanning different time scales. During the regressive periods, dipping strata were developed, while erosional surfaces and incised valleys were formed during the lowstands of sea level. Terraces, v-shaped depressions, lagoon-like structures observed on the outer continental shelf are the result of the transgressive period. In the study area we have recognised a complex erosional surface that records a long time span during the relative sea-level fall (regressive period) and the following sea-level lowstand and has been reworked during the last transgression. We also infer that sedimentation processes changed from siliciclastic sedimentation to carbonate sedimentation and again to siliciclastic sedimentation, marking an important phase in the late-Quaternary evolution of the western continental shelf of India. We attribute this to an abrupt climate change at the end of the oxygen isotope stage 2, between the Last Glacial Maximum and the Bølling-Allerod event (14?000 yr BP). This sensitive climate change (warming) favoured the formation of reefs at various depths on the shelf, besides the development of Fifty Fathom Flat, a carbonate platform on the outer shelf off Bombay developed prior to 8300 yr BP. The highstand systems tracts were deposited after the sea level reached its present position.     

长江三角洲地区晚第四纪古土壤中的植物硅酸体及其古环境意义

长江三角洲地区晚第四纪古土壤层，即以前所谓的“暗绿色硬粘上层”过去被看作是“哑地层”，本文首次发现该层中含有丰富的植物硅酸体，且各种类型的硅酸体在地层中均有出现，并在剖面上有较大的变化。在定量统计分析的基础上，利用其组合特征，并进一步利用对应分析方法，探讨了本区晚第四纪古地理、古环境变迁历史，认为该层形成子一种弱草甸环境，且在其形成过程中有四次气候冷—暖变化。