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A sequence stratigraphic model for the Lower Coal Measures (Upper Carboniferous) of the Ruhr district, north-west Germany 总被引:3,自引:0,他引:3
Upper Carboniferous Coal Measures strata have been interpreted traditionally in terms of cyclothems bounded by marine flooding surfaces (marine bands) and coal seams. Correlation of such cyclothems in an extensive grid of closely spaced coal exploration boreholes provides a robust stratigraphic framework in which to study the Lower Coal Measures (Namurian C–Westphalian A) of the Ruhr district, north-west Germany. Three distinct types of cyclothem are recognized, based on their bounding surfaces and internal facies architecture. (1) Type 1 cyclothems are bounded by marine bands. Each cyclothem comprises a thick (30–80 m), regionally extensive, coarsening-upward delta front succession of interbedded shales, siltstones and sandstones, which may be deeply incised by a major fluvial sandstone complex. The delta front succession is capped by a thin (<1 m), regionally extensive coal seam and an overlying marine band defining the top of the cyclothem. (2) Type 2 cyclothems are bounded by thick (≈1 m), regionally extensive coal seams with few splits. The basal part of a typical cyclothem comprises a thick (15–50 m), widespread, coarsening-upward delta front or lake infill succession consisting of interbedded shales, siltstones and sandstones. Networks of major (>5 km wide, 20–40 m thick), steep-sided, multistorey fluvial sandstone complexes erode deeply into and, in some cases, through these successions and are overlain by the coal seam defining the cyclothem top. (3) Type 3 cyclothems are bounded by regionally extensive coal seam groups, characterized by numerous seam splits on a local (0·1–10 km) scale. Intervening strata vary in thickness (15–60 m) and are characterized by strong local facies variability. Root-penetrated, aggradational floodplain heteroliths pass laterally into single-storey fluvial channel-fill sandstones and coarsening-upward, shallow lake infill successions of interbedded shales, siltstones and sandstones over distances of several hundred metres to a few kilometres. Narrow (<2 km) but thick (20–50 m) multistorey fluvial sandstone complexes are rare, but occur in a few type 3 cyclothems. Several cyclothems are observed to change character from type 1 to type 2 and from type 2 to type 3 up the regional palaeoslope. Consequently, we envisage a model in which each cyclothem type represents a different palaeogeographic belt within the same, idealized delta system, subject to the same allogenic and autogenic controls on facies architecture. Type 1 cyclothems are dominated by deltaic shorelines deposited during a falling stage and lowstand of sea level. Type 2 cyclothems represent the coeval lower delta plain, which was deeply eroded by incised valleys that fed the falling stage and lowstand deltas. Type 3 cyclothems comprise mainly upper delta plain deposits in which the allogenic sea-level control was secondary to autogenic controls on facies architecture. The marine bands, widespread coals and coal seam groups that bound these three cyclothem types record abandonment of the delta system during periods of rapid sea-level rise. The model suggests that the extant cyclothem paradigm does not adequately describe the detailed facies architecture of Lower Coal Measures strata. Instead, these architectures may be better understood within a high-resolution stratigraphic framework incorporating sequence stratigraphic key surfaces, integrated with depositional models derived from analogous Pleistocene–Holocene fluvio-deltaic strata. 相似文献
33.
我国东、中部地区的南北发展差异 总被引:28,自引:4,他引:24
中国东、中部地区经济发展水平由改革开放初的由北向南递减逐步演变为由南向北递减,南北区域发展差异日益突出。文章将中国东、中部地区划分为南部沿海区、长江中下游区、黄河中下游区和东北及内蒙区四个地区。从区位、政策、投资、国际化程度、中心城市、工业结构等方面分析了南北差异形成原因,对2010年各区差异作了预测,对缓解南北差异提出了具体措施。 相似文献
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林业行业应对气候变化的措施和成效 总被引:1,自引:0,他引:1
从植树造林,发挥森林吸碳和固碳作用,加强天然林保护,提高森林的碳汇潜力两大方面,陈述了林业对减缓全球气候变化的贡献。同时介绍了国家林业局在气候变化的基础科学和应用科学研究领域,开展的卓有成效的工作;介绍了国家林业局陆地生态系统定位研究网络的基础建设、与气候变化有关的科学研究的立项与课题开展情况。最后,从探讨提高森林碳汇的方法、推进加强森林碳保护的措施、寻找林产品碳替代的途径等三方面,论述了今后一段时期林业行业在减缓气候变化中的重要任务,分析中国林业在继续增加森林面积和碳汇能力方面具有的潜力。 相似文献
36.
水资源的有效保护是实现水资源可持续利用和社会经济可持续发展的重要环节。在商洛市水资源调查的基础上,合理划分水功能区,计算出重点河段各水功能分区相应的纳污能力,并以此为依据提出水资源保护措施,为商洛市水资源保护、监督和管理提供依据。 相似文献
37.
昭通头寨沟特大型灾害性滑坡研究 总被引:14,自引:0,他引:14
唐川 《云南地理环境研究》1991,3(2):64-71
昭通头寨沟滑坡具有启程剧动、行程高速、来势凶猛、破坏严重和灾害面广的特点。该滑坡是一个剧动式高速特大型岩质滑坡。本文分析了滑坡的成因和滑动的机制,根据滑坡运动后的残留痕迹和堆积地貌特征,认为头寨沟滑坡的运动方式和路径独具特点。通过对滑后斜坡稳定性的评价,说明滑坡部分残体仍有活动迹象,据此提出了滑坡的防治措施。 相似文献
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地震重点监视防御区制度,是《中华人民共和国防震减灾法》确立的法律制度.在地震重点监视防御区制度实践方面,我国已完成第一期地震重点监视防御区方案的实施,即1996年国务院批准的1996 ~2005年全国地震重点监视防御区方案.目前,正在实施的是第二期地震重点监视防御区方案,即2006年国务院批准的2006 ~2020年全国地震重点监视防御区方案.在国家社科基金重大项目支持下,本文对1996~ 2012年全国地震重点监视防御区制度的实施现状进行了追踪,对实施成效进行了总结.从1996~ 2012年的震例和调查数据看,减灾效果明显.在此基础上,提出了完善地震重点监视防御区制度的对策与建议. 相似文献
40.
The recent increase in exploration activity in the Galilee Basin, Queensland, has highlighted inconsistencies in the usage of Lopingian (upper Permian) stratigraphic nomenclature across the basin. This study utilised peer-reviewed journal, company and government publications to evaluate the current understanding of the naming conventions in use and correlated them to nomenclature in the adjacent Bowen Basin. The prominent misinterpretation is between the stratigraphic relationship and terminology of the northern and western Betts Creek beds and its eastern and southern correlatives the Bandanna Formation and Colinlea Sandstone. The correlation between the units has been assessed from a (1) lithological, (2) sedimentological and (3) coal-seam architectural perspective. The Betts Creek beds appear similar to the Colinlea Sandstone in their lithology and sedimentological character, but increased drilling data suggest the original type-sections no longer fit the heterogeneous lithology of correlated strata bearing that nomenclature. Correlation across the Springsure Shelf into the Bowen Basin suggests that the Betts Creek beds and their subdivisions are in fact equivalent to the Bandanna Formation, the Fort Cooper Coal Measures (the Burngrove and Fair Hill formations) and the Moranbah Coal Measures. A revised stratigraphic column for the Galilee Basin has been proposed to reflect this, and to suggest that a new stratigraphic unit be introduced; the ‘Fort Cooper Coal Measures equivalent’ and its subdivisions the ‘Burngrove and Fair Hill formation equivalents.’ 相似文献