In this issue, Rowland ＆ Hicks advocate a nomenclature for the four epochs of the Cambrian Period that carries over the terms Early, Middle, and Late Cambrian from previous usage （but with new definitions） and intr...In this issue, Rowland ＆ Hicks advocate a nomenclature for the four epochs of the Cambrian Period that carries over the terms Early, Middle, and Late Cambrian from previous usage （but with new definitions） and introduces a non-geographically-based term, Ichnocambrian, for the earliest Cambrian epoch. The terms Lower/Early, Middle, and Late/Upper Cambrian are confusing because they connote the second, third, and fourth epochs/series of the period/system, and because each is defined in a way that is different from traditional definitions of those intervals. The use of these terms will ultimately lead to confusion between older concepts of Early, Middle, and Late Cambrian and newer, refined concepts of the epochs. The philosophy of the International Subcommission on Cambrian Stratigraphy for establishing a clear subdivision of the Cambrian on a global scale is unambiguous： stratigraphic terms previously in use lack global applicability and should not be adopted as chronostratigraphic/geochronologic units in the developing global stratigraphic chart of the Cambrian. Moreover, all series and stage names should be GSSP （stratotype section）-based.展开更多
Following votes by the Pliensbachian Working Group, the Jurassic Subcommission and the International Commission on Stratigraphy, lUGS ratified the proposed Global Boundary Stratotype Section and Point （GSSP） for the...Following votes by the Pliensbachian Working Group, the Jurassic Subcommission and the International Commission on Stratigraphy, lUGS ratified the proposed Global Boundary Stratotype Section and Point （GSSP） for the base of the Pliensbachian Stage （Lower Jurassic） at the base of bed 73b in the Wine Haven section, Robin Hood＇s Bay, Yorkshire Coast, UK. This level contains the characteristic ammonite association Bifericeras donovani Dommergues and Meister and Apoderoceras sp. Complementary data include： a） Strontium-isotope stratigraphy, based on analysis of belemnites which yield a calcite 87Sr/^86Sr ratio for the boundary level of 0. 707425 and data supporting interpretation of continuous sedimentation; b） Belemnite oxygen-isotope data indicate a significant temperature drop （-5 ℃） across the boundary at this locality; c） A Transgressive Systems Tract （TST） initiated in the Aplanaturn Subzone （uppermost Sinemurian） continues into the Lowermost Pliensbachian （Taylori Subzone）; it forms part of a transgressive facies cycle sensu Graciansky et al. （1998）; d） The Upper Sinemurian to lowermost Plensbachian at Wine Haven section has a predominantly norreal magnetic polarity, but two discrete reversed polarity magnetozones are present. The first spans much of the latest Sinemurian Aplanatum Subzone. It terminates 〈0.5m below the Sinemurian-Pliensbachian boundary and may prove a valuable chronostratigraphic marker The second extends from the latest Oxynotum Subzone probably through to the lower part of the Raricostatum Subzone.展开更多
建立自然保护区是保护地质遗迹资源的重要手段之一,为我国地质遗迹资源的保护、研究和利用提供了最基础的保障。浙江长兴地质遗迹国家级自然保护区拥有全球最完整的二叠~三叠系界线层型剖面和点位(Global Stratotype Section and Point)...建立自然保护区是保护地质遗迹资源的重要手段之一,为我国地质遗迹资源的保护、研究和利用提供了最基础的保障。浙江长兴地质遗迹国家级自然保护区拥有全球最完整的二叠~三叠系界线层型剖面和点位(Global Stratotype Section and Point),具有极其重要的国际对比意义和科学研究价值。但是,实地调查发现,保护区管理机构在开展地质遗迹保护工作中却面临着诸多问题,如资源管护能力弱、环境监测缺失、旅游色彩浓重、土地权属复杂、机构设置不健全和管理体制不通畅等。针对这些问题,本研究提出了相应的对策建议,如构建地质剖面安全防护体系、加强地质剖面与生态环境监测、优化宣传教育系统、争取土地权属、完善职能机构和理顺管理体制等,以期为长兴地质遗迹资源的有效保护提供支持,同时也为其他存在类似问题的地质遗迹保护单位提供经验借鉴。展开更多
文摘In this issue, Rowland ＆ Hicks advocate a nomenclature for the four epochs of the Cambrian Period that carries over the terms Early, Middle, and Late Cambrian from previous usage （but with new definitions） and introduces a non-geographically-based term, Ichnocambrian, for the earliest Cambrian epoch. The terms Lower/Early, Middle, and Late/Upper Cambrian are confusing because they connote the second, third, and fourth epochs/series of the period/system, and because each is defined in a way that is different from traditional definitions of those intervals. The use of these terms will ultimately lead to confusion between older concepts of Early, Middle, and Late Cambrian and newer, refined concepts of the epochs. The philosophy of the International Subcommission on Cambrian Stratigraphy for establishing a clear subdivision of the Cambrian on a global scale is unambiguous： stratigraphic terms previously in use lack global applicability and should not be adopted as chronostratigraphic/geochronologic units in the developing global stratigraphic chart of the Cambrian. Moreover, all series and stage names should be GSSP （stratotype section）-based.
文摘Following votes by the Pliensbachian Working Group, the Jurassic Subcommission and the International Commission on Stratigraphy, lUGS ratified the proposed Global Boundary Stratotype Section and Point （GSSP） for the base of the Pliensbachian Stage （Lower Jurassic） at the base of bed 73b in the Wine Haven section, Robin Hood＇s Bay, Yorkshire Coast, UK. This level contains the characteristic ammonite association Bifericeras donovani Dommergues and Meister and Apoderoceras sp. Complementary data include： a） Strontium-isotope stratigraphy, based on analysis of belemnites which yield a calcite 87Sr/^86Sr ratio for the boundary level of 0. 707425 and data supporting interpretation of continuous sedimentation; b） Belemnite oxygen-isotope data indicate a significant temperature drop （-5 ℃） across the boundary at this locality; c） A Transgressive Systems Tract （TST） initiated in the Aplanaturn Subzone （uppermost Sinemurian） continues into the Lowermost Pliensbachian （Taylori Subzone）; it forms part of a transgressive facies cycle sensu Graciansky et al. （1998）; d） The Upper Sinemurian to lowermost Plensbachian at Wine Haven section has a predominantly norreal magnetic polarity, but two discrete reversed polarity magnetozones are present. The first spans much of the latest Sinemurian Aplanatum Subzone. It terminates 〈0.5m below the Sinemurian-Pliensbachian boundary and may prove a valuable chronostratigraphic marker The second extends from the latest Oxynotum Subzone probably through to the lower part of the Raricostatum Subzone.
文摘建立自然保护区是保护地质遗迹资源的重要手段之一,为我国地质遗迹资源的保护、研究和利用提供了最基础的保障。浙江长兴地质遗迹国家级自然保护区拥有全球最完整的二叠~三叠系界线层型剖面和点位(Global Stratotype Section and Point),具有极其重要的国际对比意义和科学研究价值。但是,实地调查发现,保护区管理机构在开展地质遗迹保护工作中却面临着诸多问题,如资源管护能力弱、环境监测缺失、旅游色彩浓重、土地权属复杂、机构设置不健全和管理体制不通畅等。针对这些问题,本研究提出了相应的对策建议,如构建地质剖面安全防护体系、加强地质剖面与生态环境监测、优化宣传教育系统、争取土地权属、完善职能机构和理顺管理体制等,以期为长兴地质遗迹资源的有效保护提供支持,同时也为其他存在类似问题的地质遗迹保护单位提供经验借鉴。
