EXPERIMENTS ON THE GROUP GENERALIZATIONG OF CONTOUR LINES FOR TOPOGRAPHIC MAPS     

FEI Lifan  Associate Professor  School of Land Science  WTUSM  Wuhan  China   《地球空间信息科学学报》1998,(1)

This paper analyzes the advantages and disadvantages of two techni-cal lines for automatic group generalization of contour lines.The author suggeststhat it is possible to get faster and better generalization results if we simulate theintelligence of human experts in program designing,retrieve geomorphologicalstructural information using the input data of 2-D contour lines and derive andoutput the generalied 2-D results directly.  相似文献   

山西大同台短水准的异常识别     

高振强 《山西地震》1998,(2):18-21

给出４点组斜率信息法的理论模型,分析了大同台短水准测量结果,证明几次中强地震前大同台短水准均有明显的中、短期异常;同时发现跨断层测站高差曲线能较好地反映震前短、临异常的变化。  相似文献   

辽宁黑山恐龙化石的发现及其地层意义   总被引：3，自引：0，他引：3  

许坤  李瑜 《地层学杂志》1998,22(3):227-231

在辽宁省黑山县八道壕煤矿沙海组下部发现一颗恐龙牙齿化石,鉴定为Ａｓｉａｔｏｓａｕｒｕｓｓｐ．,时代属早白垩世,对我国北方热河生物群时代归属研究及侏罗系－白垩系界线的划分都具有重要意义。  相似文献   

由恐龙化石论晚白垩世事件沉积   总被引：2，自引：0，他引：2  

张玉宾 《沉积学报》1998,16(2):124-128

本文根据晚白垩世恐龙化石的分布结合地层学特征,初步提出了这套含有恐龙化石的晚白垩世地层属于事件沉积的观点,并认为导致这次事件沉积的原因可能是由天体撞击地球产生的强海啸形成。  相似文献   

石棉大水沟变质岩系中微古植物化石的发现     

喻安光  陈玉禄  杨明文  杨更 《四川地质学报》1998,(4)

在大水沟一带的中浅变质碎屑岩、碳酸盐岩夹基性火山岩地层中,获得较丰富的志留纪球藻类化石,为划分地层和讨论时代归属提供了依据。  相似文献   

中国恐龙蛋化石及其生态地层浅析   总被引：2，自引：0，他引：2  

张玉光  李奎 《沉积与特提斯地质》1998,18(2):32-38

文章系统地对中国恐龙蛋化石的地理分布作了总结,并将恐龙蛋化石类型归纳为９科,１３属,２１种。在此基础上,着重分析了恐龙蛋化石古生态特征,分别从蛋化石的排列方式,恐龙产蛋的方式,不同类型蛋化石间及蛋化石与骨骼化石共生几方面作了探讨,并进一步阐述恐龙蛋化石在晚白垩世地层划分对比所具有的直接指示意义  相似文献   

河南西峡盆地恐龙蛋化石及略论恐龙绝灭问题   总被引：3，自引：0，他引：3       下载免费PDF全文

周世全  冯祖杰  王德有 《沉积与特提斯地质》1998,18(5):57-63

西峡盆地晚白垩世红色陆相碎屑岩系地层中（包括高沟组、马家村组、寺沟组）,产有类型多、数量大、成窝性好的恐龙蛋化石。已发现有７科８属１０种。自下而上,恐龙蛋的种类、数量、含蛋层数、蛋窝均大幅度地减少,由高沟组内５科６７种,约１０层含蛋层,至寺沟组内仅存１科１属２种,含蛋层为２层。恐龙绝灭原因的研究,已有３０种以上的学说或观点,但这些观点都不能圆满地解释恐龙的绝灭问题。恐龙的绝灭应该是多因素的,既有地外的灾变,又有地内,生物本身生理的因素。在内、外因等诸因素的共同作用下,恐龙才有可能绝灭。  相似文献   

北山盆地群砂岩储层特征及分类评价     

赵虹 《地球科学与环境学报》1998,(Z1)

北山盆地群侏罗系和下白垩统砂岩储层主要属长石岩屑砂岩和岩屑长石砂岩,其次为岩屑砂岩,成分和结构成熟度均较低;储层孔隙类型以次生孔隙为主,孔隙结构及物性总体较差。储层分类评价及综合分析表明,中侏罗统储层属较有利储层,在北山盆地群具有较重要的储集意义。  相似文献   

Analysis of fossil pigments from algae and bacteria in meromictic Lake Fidler, Tasmania, and its application to lake management   总被引：6，自引：0，他引：6  

Dominic A. Hodgson  Simon W. Wright  Peter A. Tyler  Noel Davies 《Journal of Paleolimnology》1998,19(1):1-22

Lake Fidler is an ectogenic meromictic lake with a monimolimnion maintained by periodic incursions of brackish water from the lower Gordon River estuary. A dam across the middle reaches of the Gordon River has restricted these incursions of brackish water and meromictic stability has rapidly declined. A palaeolimnological study was carried in order to assess the historical development of meromixis and the impact of the dam on the microbiological communities in the lake. Fossil pigments in a 17 m sediment core were analysed using reverse phase high performance liquid chromatography (rp-HPLC) and mass spectrometry (MS). In addition, taphonomic studies of pigment production, deposition and degradation in the water column and surface sediments were used to identify planktonic and benthic pigment degradation processes and constrain the stratigraphic interpretation. Results comparing the pigment composition of pelagic sediment traps and littoral surface sediments indicated that the core from the centre of the lake would permit a historical reconstruction of planktonic bacterial and algal communities. Marked increases in prokaryotic pigments ca 3500 yr B.P. suggested the possible colonisation of a chemocline by phototrophic bacteria. Further changes in chlorophyll: carotenoid ratios and changes in relative abundances of both chlorophyll a and bacteriochlorophyll c derivatives also indicated that a change in the depositional environment had occurred; possibly due to altered stratification or anoxia. From this we infer the onset of either intermittent or permanent meromixis. Further increases in prokaryotic pigment abundance suggested that the present state of permanent meromixis was firmly established by 2070 ±50 ¹⁴C yr B.P., and diatom analysis confirmed the development of a stable mixolimnion. High resolution studies of the top 10 cm of sediments measured pigments in mean concentrations of 15.1 ng g^-1 with a mean S.D. of only 2.78 indicating little change in pigment abundance since the construction of the dam. Thus, Lake Fidler still retains most of the features of meromixis. However, evidence from nearby Lake Morrison and Sulphide Pool has shown that any further declines in meromictic stability will cause a rapid reversion to holomixis. Palaeolimnological evidence from the early stages of meromictic development of Lake Fidler suggests that such reversion to holomixis may not permanently eliminate all the microbiological communities, and that, given time, they may return and prosper with re-establishment of a suitable chemocline. These studies will guide recommendations for a management strategy to prevent the further decay of meromixis in the Gordon River lakes.  相似文献   

福建省石炭纪─白垩纪古生物群主要特征     

马爱双 《福建地质》1998,(4)

通过总结福建省石炭纪─白垩纪地层中及珊瑚、腕足、双壳、菊石、叶肢介和植物等门类的古生物化石组合特征,为省内石炭纪─白垩纪地层的划分、对比提供重要的依据。  相似文献