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
The Holocene is probably the most intensively studied series/epoch within the geological record,and embodies a wide array of geomorphological,climatic,biotic and archaeological evidence;yet little attention has hither...The Holocene is probably the most intensively studied series/epoch within the geological record,and embodies a wide array of geomorphological,climatic,biotic and archaeological evidence;yet little attention has hitherto been paid to a formal subdivision of this series/epoch.Here we report a tripartite division of the Holocene into the Greenlandian,Northgrippian and Meghalayan stages/ages and their corresponding Lower/Early,Middle,Upper/Late subseries/subepochs,each supported by a Global Boundary Stratotype Section and Point(GSSP).The GSSP for the lowermost stage,the Greenlandian,is that of the Holocene as previously defined in the NGRIP2 Greenland ice core,and dated at 11,700 yr b2k(before 2000 CE).The GSSP for the Northgrippian is in the NGRIP1 Greenland ice core,and dated at 8236 yr b2k,whereas that for the Meghalayan is located in a speleothem from Mawmluh Cave,Meghalaya,northeast India with a date of 4250 yr b2k.The proposal on which this subdivision is based was submitted by the Subcommission on Quaternary Stratigraphy,approved by the International Commission on Stratigraphy,and formally ratified by the Executive Committee of the International Union of Geological Sciences on 14th June 2018.展开更多
1 Introduction Stratigraphy,placing the sequence of events in Earth history into order,is a fundamental part of the geosciences.Traditionally the starting point is a regional stratigraphy,based on lithological,mappabl...1 Introduction Stratigraphy,placing the sequence of events in Earth history into order,is a fundamental part of the geosciences.Traditionally the starting point is a regional stratigraphy,based on lithological,mappable units,correlated by fossils with local,regional and global chronostratigraphical schemes.Chronostratigraphic units were traditionally defined on their fossil content,as essentially unit stratotypes.But,commonly there were no clear boundaries.展开更多
The protection of classical or significant reference stratigraphic sections of the nation’s valuable geoheritage has become a priority by the Chinese government and national stratigraphic commission.The process for t...The protection of classical or significant reference stratigraphic sections of the nation’s valuable geoheritage has become a priority by the Chinese government and national stratigraphic commission.The process for the protection and documentation of stratigraphic sections includes:(1)marked tablets showing the standardized bed,member and formation divisions and,where applicable,standardized meter intervals for future investigations;(2)a monument or other on-site interpretive information;and(3)field guides for different audiences summarizing its importance with maps and detailed descriptions.In particular,the ten Global Stratotype Sections and Points(GSSPs)established in southern China are well preserved and managed;and some are now within tourist-friendly educational national geoparks.We suggest that other national stratigraphic commissions might incorporate some of the experiences from China’s current efforts to preserve and standardize important reference sections for Earth history research.展开更多
The Huanghuachang section near Yichang, southern China meets the requirements of Global Stratotype Section and Point (GSSP) for the base of the Middle Ordovician Series and the yet-to-be-named third stage of the Ordov...The Huanghuachang section near Yichang, southern China meets the requirements of Global Stratotype Section and Point (GSSP) for the base of the Middle Ordovician Series and the yet-to-be-named third stage of the Ordovician System (or lower stage of Middle Ordovician Series). The conodont succession at the section is complete across the Lower to Middle Ordovician series boundary and several excellent phylogenetic lineages of Baltoniodus, Trapezognathus, Periodon, and Microzarkodina are represented. The definition of the base of the Middle Ordovician is proposed to be the first appearance datum (FAD) of Baltoniodus? triangularis in the section. It is followed closely by the FAD of Microzarkodina flabellum, which is taken as a reasonable proxy for the boundary. This level approximates the boundary between the lower and upper intervals of the Azygograptus suecicus graptolite Biozone, and nearly coincides with the base of the Belonechitina henryi chitinozoan Biozone.The proposed GSSP for the base of the international Middle Ordovician Series is located in a roadside exposure at the base of Bed (SHod) 16, 10.57 m above the base of the Dawan Formation in the measured Huanghuachang section near Yichang City, southern China. The same faunal succession is also recorded from the Chenjiahe (formerly Daping) section, 5 km to the north of the Huanghuachang section. The proposed boundary horizon can be recognized and correlated globally with high precision in both relatively shallow-water carbonate facies as well as in deep-water graptolite facies.展开更多
The Global boundary Stratotype Section and Point （GSSP） for the base of the Ladinian Stage （Middle Triassic） is defined in the Caffaro river bed （45°49＇09.5＂N, 10°28＇15.5＂E）, south of the village o...The Global boundary Stratotype Section and Point （GSSP） for the base of the Ladinian Stage （Middle Triassic） is defined in the Caffaro river bed （45°49＇09.5＂N, 10°28＇15.5＂E）, south of the village of Bagolino （Province of Brescia, northern Italy）, at the base of a 15-20-cm-thick limestone bed overlying a distinct groove （＂Chiesense groove ＂） of limestone nodules in a shaly matrix, located about 5 m above the base of the Buchenstein Formation. The lower surface of the thick limestone bed has the lowest occurrence of the ammonoid Eoprotrachyceras curionii （base of the E. curionii Zone; onset of the Trachyceratidae ammonoid family）. Secondary global markers in the uppermost Anisian include the lowest occurrence of conodont Neogondolella praehungafica and a brief normal-polarity magnetic zone recognized in closely correlated sections including the principal auxiliary section at Seceda in the Dolomites. The GSSP-level is bracketed by U-Pb single zircon age data from volcaniclastic horizons, indicating a boundary age of ca 241 Ma.展开更多
Diabasbrottet, selected by the International Subcommisson on Ordovician Stratigraphy and in 2002 ratified by the International Commission on Stratigraphy as the GSSP of the Second (Upper) Stage of the Lower Ordovician...Diabasbrottet, selected by the International Subcommisson on Ordovician Stratigraphy and in 2002 ratified by the International Commission on Stratigraphy as the GSSP of the Second (Upper) Stage of the Lower Ordovician, is located on the Hunneberg Mountain in southwestern Sweden. The stratigraphic succession represents an outer shelf environment near the Baltic Shield margin. The shale-dominated, biostratigraphically complete, richly fossiliferous boundary interval is completely exposed in a disused quarry. The GSSP is in the lower TФyen Shale 2.1 m above the top of the Cambrian and is marked by the first appearance of the graptolite Tetragraptus approximatus Nicholson. The boundary interval contains a diverse graptolite fauna and biostratigraphically diagnostic conodonts and trilobites that make it possible to define the boundary in terms of zone schemes based on these groups. In this respect, the Diabasbrottet and nearby sections are unique in the world among described localities having this boundary interval. Based on the appearance of T. approximatus, the base of the Second Stage can be identified in many graptolitiferous successions round the world but this level is currently more difficult to recognize precisely in some carbonate sequences outside Baltoscandia. We propose the Second Stage be called the Floan Stage. It is named for the Village of Flo, which is situated about 5 km southeast of the GSSP.展开更多
The GSSP of the Tortonian Stage, which per definition marks the base of the Tortonian and, hence, the boundary between the Serravallian and Tortonian Stages of the Middle and Upper Miocene Subseries, has recently been...The GSSP of the Tortonian Stage, which per definition marks the base of the Tortonian and, hence, the boundary between the Serravallian and Tortonian Stages of the Middle and Upper Miocene Subseries, has recently been defined and ratified by the IUGS. The boundary stratotype-section is Monte dei Corvi (Italy) where the Tortonian GSSP is now formally at the mid-point of the sapropel of small-scale sedimentary cycle no. 76, close to the last common occurrences (LCOs) of the calcareous nannofossil Discoaster kugleri and the planktonic foraminifer Globigerinoides subquadratus and associated with the short normal subchron C5r.2n. The GSSP level coincides closely with oxygen isotope event Mi-5 and the associated glacio-eustatic sea-level low-stand of supercycle T3.1 and concurrent deep-sea hiatus NH4,and is dated astronomically at 11.608 Ma. The Monte Gibliscemi section is accepted as an auxiliary boundary stratotype because the better preservation of the calcareous microfossils in this section enables quantitative analyses and the construction of a stable isotope record.展开更多
The Niquivil section, Argentine Precordillera, fulfills most of the requirements for a Global Stratotype Section and Point （GSSP） for the base of the Middle Ordovician Series. It has excellent conodont biostratigrap...The Niquivil section, Argentine Precordillera, fulfills most of the requirements for a Global Stratotype Section and Point （GSSP） for the base of the Middle Ordovician Series. It has excellent conodont biostratigraphy in a continuous succession of uniform lithology, is readily accessible, and the critical interval is not tectonically affected. The position of the Lower/Middle Ordovician Series boundary in the Central Precordillera is placed at the middle part of the San Juan Formation, an open-platform carbonate unit. The Niquivil section is proposed as a GSSP for the base of the Middle Ordovician, which is marked by the FAD of the conodont Cooperignathus aranda （Cooper）. It occurs in level NCA, at the upper part of the Oepikodus evae Zone （overlapping uppermost records of O. evae in association with other guide species）; i.e., 100.15 m above the base of the reference section. The auxiliary Pena Sombria section from northern Precordillera records graptolites of the lower （but not lowest） Middle Ordovician in the Isograptus victoriae maximus Zone, few meters above the proposed boundary biohorizon. The range of C. aranda can be correlated with the I. victoriae lunatus Zone up to the lower part of the Undulograptus austrodentatus Zone in diverse sections of the world. C. aranda presents cosmopolitan distribution and occurs in virtually all environments. The proposed GSSP preserves a carbon-isotope record that provides an auxiliary marker of potential global application. Radiometric dating of K-bentonite samples, interbedded with carbonate strata yielding lower records of C. aranda, were recovered from the auxiliary Talacasto section in Central Precordillera （469.8 ±2.3 Ma, U-Pb SHRIMP dating）.展开更多
The Meishan Section of Changxing County, Zhejiang Province, China and the base of its Bed 27c,in which Hindeodus parvus first occurs, are recommended as the GSSP of Permian-Triassic boundary (PTB).The present paper in...The Meishan Section of Changxing County, Zhejiang Province, China and the base of its Bed 27c,in which Hindeodus parvus first occurs, are recommended as the GSSP of Permian-Triassic boundary (PTB).The present paper introduces a description of the section. Biostratigraphic correlation with other famous sections shows the completeness of this section and justifies choice of H. Parvus as the index fossil. Chemostratigraphic investigation provides the δ￣13C excursion and the moderate but inconsistent Ir spike as auxiliary symbols for the PTB. This boundary is closely related to transgression,anoxia,volcanism,mass extinction and possible impact events which can be correlated with those in South China and other parts of the world .展开更多
Sequence boundary is studied in detail in reference to the Permian Guadalupian Lopingian boundary, based on high resolution correlation of conodont zones. A conceptual synchronous stratigraphic boundary, corresponding...Sequence boundary is studied in detail in reference to the Permian Guadalupian Lopingian boundary, based on high resolution correlation of conodont zones. A conceptual synchronous stratigraphic boundary, corresponding to the age of the sequence boundary dated in the conformable portion of the sequence boundary, is defined as the sequence chronostratigraphic boundary (SCB). The sequence boundary is proved to be dual in nature in regards to tin-synchrony and diachroneity of stratigraphic boundaries. The merits of the sequence boundary in stratigraphic subdivision, correlation and classification are elucidated in comparison with the lithostratigraphic boundary, the biostratigraphic boundary and the traditional approach of the global stratotype section and point (GSSP ). By integrating the virtues of the sequence boundary and the GSSP, it is proposed that the GSSP should be established in the conformable portion of the related sequence boundary. The boundary established in light of this approach is defined as the best natural boundary. The analysis of the sequence boundary leads to the conclusion that sequence stratigraphy is a regional and transitional stratigraphic system between local lithostratigraphy and global chronostratigraphy. Therefore, a new tripartite stratigraphic classification scheme is tentatively proposed.展开更多
The Huanghuachang section near Yichang,southern China was successively approved by ISOS,recognized by ICS and then officially ratified as being the Global Stratotype Section and point(GSSP)for the base of the Middle O...The Huanghuachang section near Yichang,southern China was successively approved by ISOS,recognized by ICS and then officially ratified as being the Global Stratotype Section and point(GSSP)for the base of the Middle Ordovician Series and the Third Stage,named as Dapingian,of the Ordovician System.The conodont succession at the section is complete across the Lower to Middle Ordovician series boundary and several excellent phylogenetic lineages of Baltoniodus,Gothodus,Microzarkodina and Periodon are represented.The base of the Middle Ordovician Series and the Daping Stage is defined at a point 10.57 m above the base of the Dawan Formation at the base of Bed SHod-16 of the Huanghuachang section,22km NE of Yichang City,Hubei Province,South China.It coincides with the first appearance datum(FAD)of the conodont species Baltoniodus triangularis within the Baltoniodus lineage starting from Baltoniodus cf.B.triangularis to Baltoniodus navis.It is associated with the FAD of Periodon sp.A and followed closely by the FAD of Microzarkodina flabellum,which is taken as a reasonable proxy for the boundary.This level approxi-mates the boundary between the lower and upper Azygograptus suecicus graptolite Biozone,and nearly coincides with the base of the Belonechitina cf.henryi chitinozoan Biozone.The same faunal succession is also recorded from the Chenjiahe section,near Daping village,5 km to the north of the Huanghuachang section.展开更多
The International Commission on Stratigraphy and the IUGS Executive Committee have recently ratified a Global Standard Stratotype-section and Point(GSSP)defining the conterminous base of the third series and the fifth...The International Commission on Stratigraphy and the IUGS Executive Committee have recently ratified a Global Standard Stratotype-section and Point(GSSP)defining the conterminous base of the third series and the fifth stage of the Cambrian System.The series and the stage are respectively named the Miaolingian Series and Wuliuan Stage,after the Maioling Mountains in southeastern Guizhou and the Wuliu sidehill,Jianhe County,in eastern Guizhou Province,South China,where the GSSP is located.The GSSP is exposed in a natural outcrop near the Balang Village at a position of 26o44.843'N latitude and 108o24.830'E longitude.It is defined at the base of a silty mudstone layer 52.8 m above the base of the Kaili Formation in the Wuliu-Zengjiayan section,coinciding with the first appearance of the cosmopolitan oryctocephalid trilobite Oryctocephalus indicus(base of the O.indicus Zone).Secondary global markers at or near the base of the series and stage include the peak of a rather large negative carbon isotopic excursion(ROECE excursion),the simultaneous appearance of many acanthomorphic acritarch forms,a transgressive phase of a major eustatic event,and the last appearance of intercontinental polymerid trilobites,either Bathynotus or Ovatoryctocara.Faunal turnovers close to the base of the Miaolingian Series and Wuliuan Stage have been recognized as being at the base of the Oryctocephalus indicus Zone of Amgan Stage in Siberia,the Delamaran Stage in Laurentia,the Oryctocephalus indicus Zone in the Indian Himalaya and North Greenland,near the base of the Delamaran Stage in Australia,and within the Eccaparadocides sdzuyi Zone in Iberia and the Ornamentaspis frequens Zone in Morocco.展开更多
The Global Stratotype Section and Point(GSSP)for the Base of the Serravallian Stage(Middle Miocene)is defined in the Ras il Pellegrin section located in the coastal cliffs along the Fomm Ir-Rih Bay on the west coast o...The Global Stratotype Section and Point(GSSP)for the Base of the Serravallian Stage(Middle Miocene)is defined in the Ras il Pellegrin section located in the coastal cliffs along the Fomm Ir-Rih Bay on the west coast of Malta(35°54'50"N,14°20'10"E).The GSSP is at the base of the Blue Clay Formation(i.e.,top of the transitional bed of the uppermost Globigerina Limestone).This boundary between the Langhian and Serravallian stages coincides with the end of the major Mi-3b global cooling step in the oxygen isotopes and reflects a major increase in Antarctic ice volume,marking the end of the Middle Miocene climate transition and the Earth’s transformation into an“Icehouse”climate state.展开更多
The International Commission on Stratigraphy and the IUGS Executive Committee have recently approved a Global Standard Stratotype-section and Point(GSSP)defining the base of the second stage of the Furongian Series,Ca...The International Commission on Stratigraphy and the IUGS Executive Committee have recently approved a Global Standard Stratotype-section and Point(GSSP)defining the base of the second stage of the Furongian Series,Cambrian System.This stage is named the Jiangshanian Stage,after Jiangshan City,western Zhejiang Province,China,where the GSSP is located.The GSSP is exposed in a natural outcrop near Duibian Village.It is defined at the base of a limestone(wackestone)layer 108.12 m above the base of the Huayansi Formation in the Duibian B section,coinciding with the first appearance of the cosmopolitan agnostoid trilobite Agnostotes orientalis(base of the A.orientalis Zone).The GSSP is at a position of 28°48.977´N latitude and 118º36.887´E longitude.Secondary global markers at or near the base of the stage include the first appearance of the cosmopolitan polymerid trilobite Irvingella angustilimbata,which coincides with the FAD of the primary marker in the stratotype section,and near the end of a large positive carbon isotopic excursion(SPICE excursion).Faunal turnovers close to the base of the Jiangshanian Stage have been recognized as being at the base of the Iverian Stage in Australia,the Gonggrian Stage in Korea,and the Agnostotes orientalis–Irvingella perfecta Zone in Siberia,and near the base of the Aksayan Stage in Kazakhstan,the Sunwaptan Stage in Laurentia,and the Parabolina brevispina Zone in Baltica.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The Holocene is probably the most intensively studied series/epoch within the geological record,and embodies a wide array of geomorphological,climatic,biotic and archaeological evidence;yet little attention has hitherto been paid to a formal subdivision of this series/epoch.Here we report a tripartite division of the Holocene into the Greenlandian,Northgrippian and Meghalayan stages/ages and their corresponding Lower/Early,Middle,Upper/Late subseries/subepochs,each supported by a Global Boundary Stratotype Section and Point(GSSP).The GSSP for the lowermost stage,the Greenlandian,is that of the Holocene as previously defined in the NGRIP2 Greenland ice core,and dated at 11,700 yr b2k(before 2000 CE).The GSSP for the Northgrippian is in the NGRIP1 Greenland ice core,and dated at 8236 yr b2k,whereas that for the Meghalayan is located in a speleothem from Mawmluh Cave,Meghalaya,northeast India with a date of 4250 yr b2k.The proposal on which this subdivision is based was submitted by the Subcommission on Quaternary Stratigraphy,approved by the International Commission on Stratigraphy,and formally ratified by the Executive Committee of the International Union of Geological Sciences on 14th June 2018.
基金the Leverhulme Trust for financial support.This is a contribution to IGCP 653 project’The onset of the Great Ordovician Biodiversification Event’.
文摘1 Introduction Stratigraphy,placing the sequence of events in Earth history into order,is a fundamental part of the geosciences.Traditionally the starting point is a regional stratigraphy,based on lithological,mappable units,correlated by fossils with local,regional and global chronostratigraphical schemes.Chronostratigraphic units were traditionally defined on their fossil content,as essentially unit stratotypes.But,commonly there were no clear boundaries.
文摘The protection of classical or significant reference stratigraphic sections of the nation’s valuable geoheritage has become a priority by the Chinese government and national stratigraphic commission.The process for the protection and documentation of stratigraphic sections includes:(1)marked tablets showing the standardized bed,member and formation divisions and,where applicable,standardized meter intervals for future investigations;(2)a monument or other on-site interpretive information;and(3)field guides for different audiences summarizing its importance with maps and detailed descriptions.In particular,the ten Global Stratotype Sections and Points(GSSPs)established in southern China are well preserved and managed;and some are now within tourist-friendly educational national geoparks.We suggest that other national stratigraphic commissions might incorporate some of the experiences from China’s current efforts to preserve and standardize important reference sections for Earth history research.
文摘The Huanghuachang section near Yichang, southern China meets the requirements of Global Stratotype Section and Point (GSSP) for the base of the Middle Ordovician Series and the yet-to-be-named third stage of the Ordovician System (or lower stage of Middle Ordovician Series). The conodont succession at the section is complete across the Lower to Middle Ordovician series boundary and several excellent phylogenetic lineages of Baltoniodus, Trapezognathus, Periodon, and Microzarkodina are represented. The definition of the base of the Middle Ordovician is proposed to be the first appearance datum (FAD) of Baltoniodus? triangularis in the section. It is followed closely by the FAD of Microzarkodina flabellum, which is taken as a reasonable proxy for the boundary. This level approximates the boundary between the lower and upper intervals of the Azygograptus suecicus graptolite Biozone, and nearly coincides with the base of the Belonechitina henryi chitinozoan Biozone.The proposed GSSP for the base of the international Middle Ordovician Series is located in a roadside exposure at the base of Bed (SHod) 16, 10.57 m above the base of the Dawan Formation in the measured Huanghuachang section near Yichang City, southern China. The same faunal succession is also recorded from the Chenjiahe (formerly Daping) section, 5 km to the north of the Huanghuachang section. The proposed boundary horizon can be recognized and correlated globally with high precision in both relatively shallow-water carbonate facies as well as in deep-water graptolite facies.
文摘The Global boundary Stratotype Section and Point （GSSP） for the base of the Ladinian Stage （Middle Triassic） is defined in the Caffaro river bed （45°49＇09.5＂N, 10°28＇15.5＂E）, south of the village of Bagolino （Province of Brescia, northern Italy）, at the base of a 15-20-cm-thick limestone bed overlying a distinct groove （＂Chiesense groove ＂） of limestone nodules in a shaly matrix, located about 5 m above the base of the Buchenstein Formation. The lower surface of the thick limestone bed has the lowest occurrence of the ammonoid Eoprotrachyceras curionii （base of the E. curionii Zone; onset of the Trachyceratidae ammonoid family）. Secondary global markers in the uppermost Anisian include the lowest occurrence of conodont Neogondolella praehungafica and a brief normal-polarity magnetic zone recognized in closely correlated sections including the principal auxiliary section at Seceda in the Dolomites. The GSSP-level is bracketed by U-Pb single zircon age data from volcaniclastic horizons, indicating a boundary age of ca 241 Ma.
文摘Diabasbrottet, selected by the International Subcommisson on Ordovician Stratigraphy and in 2002 ratified by the International Commission on Stratigraphy as the GSSP of the Second (Upper) Stage of the Lower Ordovician, is located on the Hunneberg Mountain in southwestern Sweden. The stratigraphic succession represents an outer shelf environment near the Baltic Shield margin. The shale-dominated, biostratigraphically complete, richly fossiliferous boundary interval is completely exposed in a disused quarry. The GSSP is in the lower TФyen Shale 2.1 m above the top of the Cambrian and is marked by the first appearance of the graptolite Tetragraptus approximatus Nicholson. The boundary interval contains a diverse graptolite fauna and biostratigraphically diagnostic conodonts and trilobites that make it possible to define the boundary in terms of zone schemes based on these groups. In this respect, the Diabasbrottet and nearby sections are unique in the world among described localities having this boundary interval. Based on the appearance of T. approximatus, the base of the Second Stage can be identified in many graptolitiferous successions round the world but this level is currently more difficult to recognize precisely in some carbonate sequences outside Baltoscandia. We propose the Second Stage be called the Floan Stage. It is named for the Village of Flo, which is situated about 5 km southeast of the GSSP.
文摘The GSSP of the Tortonian Stage, which per definition marks the base of the Tortonian and, hence, the boundary between the Serravallian and Tortonian Stages of the Middle and Upper Miocene Subseries, has recently been defined and ratified by the IUGS. The boundary stratotype-section is Monte dei Corvi (Italy) where the Tortonian GSSP is now formally at the mid-point of the sapropel of small-scale sedimentary cycle no. 76, close to the last common occurrences (LCOs) of the calcareous nannofossil Discoaster kugleri and the planktonic foraminifer Globigerinoides subquadratus and associated with the short normal subchron C5r.2n. The GSSP level coincides closely with oxygen isotope event Mi-5 and the associated glacio-eustatic sea-level low-stand of supercycle T3.1 and concurrent deep-sea hiatus NH4,and is dated astronomically at 11.608 Ma. The Monte Gibliscemi section is accepted as an auxiliary boundary stratotype because the better preservation of the calcareous microfossils in this section enables quantitative analyses and the construction of a stable isotope record.
文摘The Niquivil section, Argentine Precordillera, fulfills most of the requirements for a Global Stratotype Section and Point （GSSP） for the base of the Middle Ordovician Series. It has excellent conodont biostratigraphy in a continuous succession of uniform lithology, is readily accessible, and the critical interval is not tectonically affected. The position of the Lower/Middle Ordovician Series boundary in the Central Precordillera is placed at the middle part of the San Juan Formation, an open-platform carbonate unit. The Niquivil section is proposed as a GSSP for the base of the Middle Ordovician, which is marked by the FAD of the conodont Cooperignathus aranda （Cooper）. It occurs in level NCA, at the upper part of the Oepikodus evae Zone （overlapping uppermost records of O. evae in association with other guide species）; i.e., 100.15 m above the base of the reference section. The auxiliary Pena Sombria section from northern Precordillera records graptolites of the lower （but not lowest） Middle Ordovician in the Isograptus victoriae maximus Zone, few meters above the proposed boundary biohorizon. The range of C. aranda can be correlated with the I. victoriae lunatus Zone up to the lower part of the Undulograptus austrodentatus Zone in diverse sections of the world. C. aranda presents cosmopolitan distribution and occurs in virtually all environments. The proposed GSSP preserves a carbon-isotope record that provides an auxiliary marker of potential global application. Radiometric dating of K-bentonite samples, interbedded with carbonate strata yielding lower records of C. aranda, were recovered from the auxiliary Talacasto section in Central Precordillera （469.8 ±2.3 Ma, U-Pb SHRIMP dating）.
文摘The Meishan Section of Changxing County, Zhejiang Province, China and the base of its Bed 27c,in which Hindeodus parvus first occurs, are recommended as the GSSP of Permian-Triassic boundary (PTB).The present paper introduces a description of the section. Biostratigraphic correlation with other famous sections shows the completeness of this section and justifies choice of H. Parvus as the index fossil. Chemostratigraphic investigation provides the δ￣13C excursion and the moderate but inconsistent Ir spike as auxiliary symbols for the PTB. This boundary is closely related to transgression,anoxia,volcanism,mass extinction and possible impact events which can be correlated with those in South China and other parts of the world .
基金This study is sponsored by the "SSLC", a state key project supported by the State Science and Technology Committee of China and the Ministry of Geology and Mineral Resources
文摘Sequence boundary is studied in detail in reference to the Permian Guadalupian Lopingian boundary, based on high resolution correlation of conodont zones. A conceptual synchronous stratigraphic boundary, corresponding to the age of the sequence boundary dated in the conformable portion of the sequence boundary, is defined as the sequence chronostratigraphic boundary (SCB). The sequence boundary is proved to be dual in nature in regards to tin-synchrony and diachroneity of stratigraphic boundaries. The merits of the sequence boundary in stratigraphic subdivision, correlation and classification are elucidated in comparison with the lithostratigraphic boundary, the biostratigraphic boundary and the traditional approach of the global stratotype section and point (GSSP ). By integrating the virtues of the sequence boundary and the GSSP, it is proposed that the GSSP should be established in the conformable portion of the related sequence boundary. The boundary established in light of this approach is defined as the best natural boundary. The analysis of the sequence boundary leads to the conclusion that sequence stratigraphy is a regional and transitional stratigraphic system between local lithostratigraphy and global chronostratigraphy. Therefore, a new tripartite stratigraphic classification scheme is tentatively proposed.
基金Research on the Huanghuachang GSSP and preparation of this proposal was financially supported by the China Geological Survey(NO:200113900072)National Natural Science Foundation of China(NO:40272020)the Germany Academic exchange Centre(DAAD),Chinese Commission of Stratigraphy and Yichang Institute of Geology and Mineral Resources(YIGMR).
文摘The Huanghuachang section near Yichang,southern China was successively approved by ISOS,recognized by ICS and then officially ratified as being the Global Stratotype Section and point(GSSP)for the base of the Middle Ordovician Series and the Third Stage,named as Dapingian,of the Ordovician System.The conodont succession at the section is complete across the Lower to Middle Ordovician series boundary and several excellent phylogenetic lineages of Baltoniodus,Gothodus,Microzarkodina and Periodon are represented.The base of the Middle Ordovician Series and the Daping Stage is defined at a point 10.57 m above the base of the Dawan Formation at the base of Bed SHod-16 of the Huanghuachang section,22km NE of Yichang City,Hubei Province,South China.It coincides with the first appearance datum(FAD)of the conodont species Baltoniodus triangularis within the Baltoniodus lineage starting from Baltoniodus cf.B.triangularis to Baltoniodus navis.It is associated with the FAD of Periodon sp.A and followed closely by the FAD of Microzarkodina flabellum,which is taken as a reasonable proxy for the boundary.This level approxi-mates the boundary between the lower and upper Azygograptus suecicus graptolite Biozone,and nearly coincides with the base of the Belonechitina cf.henryi chitinozoan Biozone.The same faunal succession is also recorded from the Chenjiahe section,near Daping village,5 km to the north of the Huanghuachang section.
基金supported in part by grants from the National Natural Science Foundation of China(49060010,40372023,41330101)the Ministry of Science and Technology of China(2006CB806401,2013CB835002,2015FY310100,12002CC2600)+3 种基金the National Commission on Stratigraphy of China(95-Special Project-01-1-6,DD20160120-04)the State Key Laboratory on Palaeobiology and Stratigraphy(20191101)the Guizhou Bureau of Science and Technology(CGSCFG-2010-7001Gui.Sci.Tal.[2017]5788)。
文摘The International Commission on Stratigraphy and the IUGS Executive Committee have recently ratified a Global Standard Stratotype-section and Point(GSSP)defining the conterminous base of the third series and the fifth stage of the Cambrian System.The series and the stage are respectively named the Miaolingian Series and Wuliuan Stage,after the Maioling Mountains in southeastern Guizhou and the Wuliu sidehill,Jianhe County,in eastern Guizhou Province,South China,where the GSSP is located.The GSSP is exposed in a natural outcrop near the Balang Village at a position of 26o44.843'N latitude and 108o24.830'E longitude.It is defined at the base of a silty mudstone layer 52.8 m above the base of the Kaili Formation in the Wuliu-Zengjiayan section,coinciding with the first appearance of the cosmopolitan oryctocephalid trilobite Oryctocephalus indicus(base of the O.indicus Zone).Secondary global markers at or near the base of the series and stage include the peak of a rather large negative carbon isotopic excursion(ROECE excursion),the simultaneous appearance of many acanthomorphic acritarch forms,a transgressive phase of a major eustatic event,and the last appearance of intercontinental polymerid trilobites,either Bathynotus or Ovatoryctocara.Faunal turnovers close to the base of the Miaolingian Series and Wuliuan Stage have been recognized as being at the base of the Oryctocephalus indicus Zone of Amgan Stage in Siberia,the Delamaran Stage in Laurentia,the Oryctocephalus indicus Zone in the Indian Himalaya and North Greenland,near the base of the Delamaran Stage in Australia,and within the Eccaparadocides sdzuyi Zone in Iberia and the Ornamentaspis frequens Zone in Morocco.
文摘The Global Stratotype Section and Point(GSSP)for the Base of the Serravallian Stage(Middle Miocene)is defined in the Ras il Pellegrin section located in the coastal cliffs along the Fomm Ir-Rih Bay on the west coast of Malta(35°54'50"N,14°20'10"E).The GSSP is at the base of the Blue Clay Formation(i.e.,top of the transitional bed of the uppermost Globigerina Limestone).This boundary between the Langhian and Serravallian stages coincides with the end of the major Mi-3b global cooling step in the oxygen isotopes and reflects a major increase in Antarctic ice volume,marking the end of the Middle Miocene climate transition and the Earth’s transformation into an“Icehouse”climate state.
基金supported in part by grants from the State Key Laboratory on Palaeobiology and Stratigraphy,(2009110320121101)+2 种基金the Ministry of Science and Technology of China(2006FY120300)the National Natural Science Foundation of China(41290260,41221001)the National Commission on Stratigraphy of China to Peng.
文摘The International Commission on Stratigraphy and the IUGS Executive Committee have recently approved a Global Standard Stratotype-section and Point(GSSP)defining the base of the second stage of the Furongian Series,Cambrian System.This stage is named the Jiangshanian Stage,after Jiangshan City,western Zhejiang Province,China,where the GSSP is located.The GSSP is exposed in a natural outcrop near Duibian Village.It is defined at the base of a limestone(wackestone)layer 108.12 m above the base of the Huayansi Formation in the Duibian B section,coinciding with the first appearance of the cosmopolitan agnostoid trilobite Agnostotes orientalis(base of the A.orientalis Zone).The GSSP is at a position of 28°48.977´N latitude and 118º36.887´E longitude.Secondary global markers at or near the base of the stage include the first appearance of the cosmopolitan polymerid trilobite Irvingella angustilimbata,which coincides with the FAD of the primary marker in the stratotype section,and near the end of a large positive carbon isotopic excursion(SPICE excursion).Faunal turnovers close to the base of the Jiangshanian Stage have been recognized as being at the base of the Iverian Stage in Australia,the Gonggrian Stage in Korea,and the Agnostotes orientalis–Irvingella perfecta Zone in Siberia,and near the base of the Aksayan Stage in Kazakhstan,the Sunwaptan Stage in Laurentia,and the Parabolina brevispina Zone in Baltica.
