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91.
浙江省上石炭统-中二叠统生物地层划分进展   总被引:2,自引:0,他引:2  
本文划分论述了浙江省上石炭统—中二叠统16条化石带(其中11条为新建化石带),对比研究结果表明它们分布于老虎洞组、黄龙组、船山组、梁山组、栖霞组、孤峰组、龙潭组下部的地层,可分别与滑石板阶、达拉阶、逍遥阶、紫松阶、隆林阶、栖霞阶、祥播阶、茅口阶、冷坞阶等9个阶对比。探讨研究了上石炭统底界、下二叠统底界和中二叠统底界;指出上石炭统未见底,缺失罗苏期的沉积;下二叠统底界位于Sphaeroschwagerina subrotunda带之底,以Sphaeroschwagerina属的始现作为底界的标准;石炭—二叠系界线位于Triticites subcrassulu筵带与Sphaeroschwagerina subrotund筵带之间;中二叠统的底界位于Orthotichia chekiangensis腕足组合带之底,以Orthotichia chekiangensis的始现作为中二叠统底界的标准。进一步论证了船山组是一个跨越石炭—二叠系界线的岩石地层单位,下部归属上石炭统逍遥阶,中部归属下二叠统紫松阶和上部归属下二叠统隆林阶。  相似文献   
92.
本区石炭系的研究以下扬子区为主,而该区又是以宁镇山脉为标准。已有半个多世纪的研究历史。目前一般将石炭系分为金陵组:高骊山组、和州组,老虎洞组、黄龙组和船山组六个组。前四个组相当于下统一丰宁统,后二个组相当于上统一壶天统。两统之间呈假整合。过去,下统是以珊瑚为标准 上统则以(?)带为分层依据。实际上腕足类有些属种也具有重要的分层价值。本文除老虎洞组、船山组资料不够未建腕足类组合外,金陵组至黄龙组暂建五个腕足类组合。即Neospirifer lungtanensis组合,Eochoristites-Martininella chinglungensis组合,Pugilis hunanensis-Vitiliprod-uctus groberi组合、Gigantoproductus edelburgensis-Kansuella组合及Choristites组合。  相似文献   
93.
文玉芳 《四川环境》1994,13(4):53-56
本文对乌江下游沿河到彭水段河水,底质,鱼肉,岩坡土壤和木本植物叶片中汞的含量分布情况作了较全面的调查,结果表明乌江下游沿河至彭水段河水汞含量为0.035-0.05μg/l,底质派含量为131-369μg/kg,鱼肉汞含量为10.5-17.5μg/kg,岸坡土壤汞含量为53.0-2904μg/kg,岩坡木本植物叶片汞含量为18.7-93.5μg/kg,汞含量序为,岸坡封>底质>鱼肉>岸坡木本植物叶>河水。  相似文献   
94.
对275名邮局分拣工的调查发现,其慢性肌肉骨骼损伤主要涉及手、腕、臂、肩、上背及下背,与对照人群比较,P〈0.05,差别显著。另外腱鞘囊肿的检出率达4.73% ,明显高于对照人群  相似文献   
95.
96.
A study was conducted to assess the ecosystem health of Lower Songkhram wetland in Thailand, using a newly developed wetland ecosystem health index (WEHI) based on analysis of field survey and secondary data of the most dominant physical, environmental and socio-economic factors extracted by principal components analysis (PCA). The most influential physical, environmental and socio-economic factors identified were rainfall and awareness and participation of the local community, which had positive effects, whereas soil electrical conductivity (EC), biochemical oxygen demand (BOD) and urban development had negative effects. Based on the results, 9 of the 40 land units of the study area were in very good or good health, 11 in reasonable health, while 20 were found to be in poor or even very poor condition. These findings will be useful for decision-makers in planning and executing an effective and holistic strategy to prevent further wetland degradation.  相似文献   
97.
二叠-三叠纪生物绝灭事件在地史发展中有着重要作用,灭绝加速了物种的进化和更替。本文简要总结了近几年来全球地球化学、地质和古生物等学者关于P-T生物绝灭事件的研究,包括事件的测年研究进展和事件原因的种种学说,其中详细阐述了地外碰撞(小行星或彗星)、火山学说、缺氧学说以及海洋酸性化假设的研究进展,并对该绝灭事件研究意义进行了简单的分析和探讨。  相似文献   
98.
张清 《灾害学》1992,7(3):73-76
本文研究了近40a来我国长江中下游地区春季低温的气侯特征,同时给出了研究低温的定量指标,并就低温对早稻产量的影响进行了初步探讨。  相似文献   
99.
The Lower Rio Grande Valley (LRGV) region in South Texas emerges as a warehouse and transportation center between Central America and the US with positive growth impacts due to the North American Free Trade Agreement (NAFTA). In 10 years time, a 39.8% population increase has resulted in a 25% boost in solid waste per capita disposal rate in the region. A landfill space shortage drives a need for landfill operators to understand their optimal management strategies in this highly-competitive market. Initially, a strategic plan for optimal solid waste pattern distribution minimizes net costs for cities. This is accomplished through a grey integer programming algorithm that encapsulates all uncertainty present in the solid waste system. Secondly, a series of grey integer submodels construct payoff matrices for a zero-sum two-person game. The ensuing game theoretic analysis is critical for evaluating optimal pricing strategies for tipping fees available to the most significant regional landfills (e.g. Browning-Ferris Industries (BFI) and City of Edinburg) as they compete over disposal contracts. The BFI landfill intrinsically benefits from its competitive pricing policy and central location to solid waste generators. The City of Edinburg landfill, on the other hand, wishes to secure its lucrative solid waste management revenue. It desires a gaming strategy backed by optimality that integrates ambiguity in solid waste generation, design capacity boundaries, and unitary shipping costs. Results show that a two-tiered analysis via grey integer programming-based games may pave the way for 'grey Nash equilibria' pricing tactics that will help the Edinburg landfill maintain its waste contracts.  相似文献   
100.
Forest succession is the base of establishing restoration reference which plays an important role in forest restoration and restoration estimation. The study presented the establishment of a Markov successional model (MSM) and its application to restoration reference in lower subtropical forest in China. The compositions of successional system in MSM were divided into three species types: pioneering pine trees, heliophytic trees and mesophytic trees. The successional system was divided into three subsystems: early successional stage, mid-successional stage and late-successional stage. Based on the site survey on the changes in the species and their individuals in 25 years, the transition matrices in various subsystems were determined. The predicted results were used to establish the restoration reference of the vegetation restoration in lower subtropical China. According to the ecological restoration reference established in this study, it would take 150 years for the forest to change from pioneer to mature communities in the region. Successional change of tree composition was forecast by the model, and the scenario forecast by the model reflects the actual conditions observed through 52 years of long-term permanent site research. The restoration experience in the region matches the forecast results. The application of a restoration reference model indicates that forest restoration can be accelerated by taking measures which change forest structure. The above results imply that a restoration reference established on the rule of regional forest succession could be very useful not only in directing, but also in assessing and managing regional forest restoration. Previously, one “ideal reference ecosystem” was used as a restoration reference in all correlative studies. In this study, the restoration “process” was used as the restoration reference.  相似文献   
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