简要介绍"国际地层表"(2008)对"国际地层表"(2004)作出的一些修改:恢复了第四系,完善了下古生界与前寒武系的年代地层单位系统,增加了14枚金钉子,更新了一些同位素年龄数据。为了使读者了解更多磁性地层学与全球海...简要介绍"国际地层表"(2008)对"国际地层表"(2004)作出的一些修改:恢复了第四系,完善了下古生界与前寒武系的年代地层单位系统,增加了14枚金钉子,更新了一些同位素年龄数据。为了使读者了解更多磁性地层学与全球海平面变化的情况,在刊出"国际地层表(International Stratigraphic Chart)"(2008)的同时还附上了"地质年代表(Geologic Time Scale)"(2008)。展开更多
The Global boundary Stratotype Section and Point （GSSP） for the base of the Hirnantian Stage （the uppermost of the Ordovician System） is defined at a point 0.39m below the base of the Kuanyinchiao Bed in the Wangj...The Global boundary Stratotype Section and Point （GSSP） for the base of the Hirnantian Stage （the uppermost of the Ordovician System） is defined at a point 0.39m below the base of the Kuanyinchiao Bed in the Wangjiawan North section. The section is located near Wangjiawan village, 42 km north of Yichang city （western Hubei, China）, at 30° 58′56″N and 111° 25′10″E. The GSSP level coincides with the first appearance of the graptolite species Normalograptus extraordinarius （Sobolevskaya）. Secondary markers include the onset of a positive carbon-isotope excursion, and a slightly earlier first appearance of Normalograptus ojsuensis （ Koren and Mikhailova ）. The Wangjiawan North section possesses continuity of sedimentation and biozonation with completeness of exposures, abundant and well-preserved graptolites and shelly fossils, i. e. the Hirnantia- Dalmanitina shelly fauna which is a key element for recognition of the Hirnantian Stage. The Wangjiawan North, South and Riverside sections possess favorable facies and widespread correlation potential, are free from structure complication, metamorphism and other alteration, and have good accessibility. The Riverside section in particular possesses amenability to isotopic age determination. The beginning of the Hirnantian was followed by a global episode of a major extinction event, which happened in the Diceratograptus mirus Subzone. The proposal was voted by the International Subcommission on Ordovician Stratigraphy in October, 2004, approved by the International Commission on Stratigraphy in February, 2006, and ratified by the International Union of Geological Sciences in May, 2006.展开更多
The Global Stratotype Section and Point （GSSP） for the base-Changhsingian Stage is defined at the First Appearance Datum （FAD） of the conodont Clarkina wangi within the lineage from C. longicuspidata to C. wangi a...The Global Stratotype Section and Point （GSSP） for the base-Changhsingian Stage is defined at the First Appearance Datum （FAD） of the conodont Clarkina wangi within the lineage from C. longicuspidata to C. wangi at a point 88 cm above the base of the Changxing Limestone in the lower part of Bed 4 （base of 4α-2） at Meishan D section, Changxing County, Zhejiang Province, South China. This level is consistent with the first appearance of Changhsingian index fusulinid Palaeofusulina sinensis and tapashanitid ammonoids. The speciation event from Clarkina longicuspidata to C. wangi occurs just above the flooding surface of the second parasequence in the Changxing Limestone. In addition, the boundary interval is clearly recognizable by the depletion of isotopic carbon ratios and the normal polarity zone appearing above the Late Wuchiapingian reversed polarity zone. Section C, about 300 m to the west of Section D, exposes more of the upper Longtan Formation. It clearly shows the transitional nature of deposition across the Longtan/Changxing formational boundary, and thus is described as a supplementary reference section.展开更多
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
对已确立的“金钉子”建立全球辅助界线层型剖面和点位(俗称“银钉子”),世界各国学者一般没有异议,但对建立“银钉子”的理念、技术要求和批准程序,以及“银钉子”应该起什么样的辅助作用,认识很不一致。这个问题本来不太受重视,但随...对已确立的“金钉子”建立全球辅助界线层型剖面和点位(俗称“银钉子”),世界各国学者一般没有异议,但对建立“银钉子”的理念、技术要求和批准程序,以及“银钉子”应该起什么样的辅助作用,认识很不一致。这个问题本来不太受重视,但随着近年来“金钉子”(全球界线层型剖面和点位,GlobalBoundary Stratotype Section and Point, GSSP)工程接近完成、后层型研究不断深入而变得越来越重要。展开更多
文摘简要介绍"国际地层表"(2008)对"国际地层表"(2004)作出的一些修改:恢复了第四系,完善了下古生界与前寒武系的年代地层单位系统,增加了14枚金钉子,更新了一些同位素年龄数据。为了使读者了解更多磁性地层学与全球海平面变化的情况,在刊出"国际地层表(International Stratigraphic Chart)"(2008)的同时还附上了"地质年代表(Geologic Time Scale)"(2008)。
文摘The Global boundary Stratotype Section and Point （GSSP） for the base of the Hirnantian Stage （the uppermost of the Ordovician System） is defined at a point 0.39m below the base of the Kuanyinchiao Bed in the Wangjiawan North section. The section is located near Wangjiawan village, 42 km north of Yichang city （western Hubei, China）, at 30° 58′56″N and 111° 25′10″E. The GSSP level coincides with the first appearance of the graptolite species Normalograptus extraordinarius （Sobolevskaya）. Secondary markers include the onset of a positive carbon-isotope excursion, and a slightly earlier first appearance of Normalograptus ojsuensis （ Koren and Mikhailova ）. The Wangjiawan North section possesses continuity of sedimentation and biozonation with completeness of exposures, abundant and well-preserved graptolites and shelly fossils, i. e. the Hirnantia- Dalmanitina shelly fauna which is a key element for recognition of the Hirnantian Stage. The Wangjiawan North, South and Riverside sections possess favorable facies and widespread correlation potential, are free from structure complication, metamorphism and other alteration, and have good accessibility. The Riverside section in particular possesses amenability to isotopic age determination. The beginning of the Hirnantian was followed by a global episode of a major extinction event, which happened in the Diceratograptus mirus Subzone. The proposal was voted by the International Subcommission on Ordovician Stratigraphy in October, 2004, approved by the International Commission on Stratigraphy in February, 2006, and ratified by the International Union of Geological Sciences in May, 2006.
文摘The Global Stratotype Section and Point （GSSP） for the base-Changhsingian Stage is defined at the First Appearance Datum （FAD） of the conodont Clarkina wangi within the lineage from C. longicuspidata to C. wangi at a point 88 cm above the base of the Changxing Limestone in the lower part of Bed 4 （base of 4α-2） at Meishan D section, Changxing County, Zhejiang Province, South China. This level is consistent with the first appearance of Changhsingian index fusulinid Palaeofusulina sinensis and tapashanitid ammonoids. The speciation event from Clarkina longicuspidata to C. wangi occurs just above the flooding surface of the second parasequence in the Changxing Limestone. In addition, the boundary interval is clearly recognizable by the depletion of isotopic carbon ratios and the normal polarity zone appearing above the Late Wuchiapingian reversed polarity zone. Section C, about 300 m to the west of Section D, exposes more of the upper Longtan Formation. It clearly shows the transitional nature of deposition across the Longtan/Changxing formational boundary, and thus is described as a supplementary reference section.
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.
文摘对已确立的“金钉子”建立全球辅助界线层型剖面和点位(俗称“银钉子”),世界各国学者一般没有异议,但对建立“银钉子”的理念、技术要求和批准程序,以及“银钉子”应该起什么样的辅助作用,认识很不一致。这个问题本来不太受重视,但随着近年来“金钉子”(全球界线层型剖面和点位,GlobalBoundary Stratotype Section and Point, GSSP)工程接近完成、后层型研究不断深入而变得越来越重要。
