The International Stratigraphic Guide defined that all stratified or quasi-stratified rock bodies of the earth crust, including sedimentary, igneous, metamorphic, solidified and unsolidified ones, should be considered...The International Stratigraphic Guide defined that all stratified or quasi-stratified rock bodies of the earth crust, including sedimentary, igneous, metamorphic, solidified and unsolidified ones, should be considered as research contents of stratigraphy. Traditional stratigraphy mainly involves strata formed under gravity mechanism, plus a few kinds of bedded volcanic rocks such as lava, pyroclastic rock and volcanic ash, as well as metamorphic sedimentary and volcano-sedimentary rocks. These traditional strata are regarded as Smithian strata in this paper. In modern stratigraphy, mechanism of strata formation includes not only gravity but also thermal (ophiolite), mechanic and tectonic forces (orogenic mélange and tectonite). In these above-mentioned non-gravitative conditions, the strata, formed complying with their own mechanisms but not with the law of superposition of Smithian stratigraphy, are called non-Smithian strata here. In mélange regions from orogenic belt, formations of non-Smithian strata could be classified into subduct-scrape-match, subduct-return-match, and subduct- overthrust types.展开更多
Since the West Pingdingshan Section in Chaohu was proposed as the candidate of the Global Stratotype Section and Point of the Induan-Olenekian boundary in 2003, the Lower Triassic of Chaohu has been extensively studie...Since the West Pingdingshan Section in Chaohu was proposed as the candidate of the Global Stratotype Section and Point of the Induan-Olenekian boundary in 2003, the Lower Triassic of Chaohu has been extensively studied. Based on the studies on the Lower Triassic of Chaohu, （1） a continuous conodont zonation is established, which has become an important reference for Lower Triassic stratigraphic correlation over the world; （2） the First Appearance Datum of conodont Neospathodus waageni was suggested and has been basically accepted as the primary marker to define the InduanOienekian boundary; （3） a characteristic Lower Triassic excursion of carbon isotopes was brought to light and has been proven to be not only an excellent index for the stratigraphic correlation but also a unique indication for the perturbation of ecological environments in the aftermath of the end-Permian mass extinction; （4） a magnetostratigraphic sequence is constituted with a certain biostratigraphic control in the low-latitude region and it presents an important correlation to the Boreal sequence; （5） a cyclostratigraphic study provides an alternative method to constrain the age of the chronostratigraphic units; and （6） a scheme of the Olenekian subdivision is recently suggested to define the boundary between the Smithian and Spathian Substages. In addition, Chaohu is also the type locality of the Chaohuan Stage, the upper stage of the Lower Triassic in the China Chronostratigraphic System.Thus, the Lower Triassic of Chaohu is not only a classic sequence in South China, but also a key reference sequence to the investigation of the corresponding stratigraphy and geological events over the world. The recent achievements are viewed here for an overall understanding of the sequence. Then the current situation of the Induan-Olenekian and Smithian-Spathian boundaries is discussed to provide a reference for later works.展开更多
Information on latest early Olenekian(latest Smithian)ammonoids is available apparently from only seven regions of the world,including South Primorye.Latest Smithian evidences on this topic are recorded from the West ...Information on latest early Olenekian(latest Smithian)ammonoids is available apparently from only seven regions of the world,including South Primorye.Latest Smithian evidences on this topic are recorded from the West SMID(abbreviation from the Russian name of the quarry:"Building Materials and Details"),East SMID and Golyj Cape areas in South Primorye.This provides additional information on systematic composition of latest Smithian ammonoid,as well as conodont and brachiopod assemblages from the recently identified Shimanskyites shimanskyi Zone,located between lower Olenekian Anasibirites nevolini Zone and upper Olenekian Tirolites subcassianus Zone.There are many common ammonoid species in the Shimanskyites shimanskyi Zone and the underlying Anasibirites nevolini Zone,e.g.,Prosphingitoides sp.,Arctoceras septentrionale(Diener),Churkites syskoi Zakharov et Shigeta,Submeekoceras?subhhydaspis(Kiparisova),Prionites markevichi Zakharov et Smyshlyaeva,?Anasibirites?simanenkoi Zakharov et Smyshlyaeva,Xenoceltites?subvariocostatus Zakharov et Smyshlyaeva,and Mianwaliites zimini Zakharov et Smyshlyaeva.The base of the Shimanskyites shimanskyi Zone,marked by a negativeδ13Corg excursion in the Kamenushka-2 Section by our previous study,coincides with the FO(first occurrence)of ammonoids Shimanskyites shimanskyi Zakharov et Smyshlyaeva and Glyptophiceras cf.sinuatum(Waagen)and conodont Hindeodella budurovi Buryi.This zone is characterized additionally by some fossils common for the overlying upper Olenekian Tirolites subcassianus Zone:ammonoids of the genus Kamenushkaites,brachiopods Bittnerihyris margaritovi(Bittner)and Lepismatina sp.and conodont?Neogondolella?(=?Borinella)jubata Sweet.The latest Smithian ammonoids recorded from the Shimanskyites shimanskyi Zone totally consist of 30 taxa belonging to 11 families(Sageceratidae,Ussuiriidae,Aspenitidae,Paranannitidae,Arctoceratidae,Proptychitidae,?Galfetitidae,Prionitidae,?Kashmiritidae,Xenoceltitidae and Palaeophyllitidae).The problems of global correlation of uppermost Smithian strata are also discussed.展开更多
文摘The International Stratigraphic Guide defined that all stratified or quasi-stratified rock bodies of the earth crust, including sedimentary, igneous, metamorphic, solidified and unsolidified ones, should be considered as research contents of stratigraphy. Traditional stratigraphy mainly involves strata formed under gravity mechanism, plus a few kinds of bedded volcanic rocks such as lava, pyroclastic rock and volcanic ash, as well as metamorphic sedimentary and volcano-sedimentary rocks. These traditional strata are regarded as Smithian strata in this paper. In modern stratigraphy, mechanism of strata formation includes not only gravity but also thermal (ophiolite), mechanic and tectonic forces (orogenic mélange and tectonite). In these above-mentioned non-gravitative conditions, the strata, formed complying with their own mechanisms but not with the law of superposition of Smithian stratigraphy, are called non-Smithian strata here. In mélange regions from orogenic belt, formations of non-Smithian strata could be classified into subduct-scrape-match, subduct-return-match, and subduct- overthrust types.
基金supported by the Ministry of Science and Technology project (no. 2006FY120300-11)Ministry of Education project (no. 200804910503)National Natural Science Foundation of China (nos. 40830212, 40921062, 40972003)
文摘Since the West Pingdingshan Section in Chaohu was proposed as the candidate of the Global Stratotype Section and Point of the Induan-Olenekian boundary in 2003, the Lower Triassic of Chaohu has been extensively studied. Based on the studies on the Lower Triassic of Chaohu, （1） a continuous conodont zonation is established, which has become an important reference for Lower Triassic stratigraphic correlation over the world; （2） the First Appearance Datum of conodont Neospathodus waageni was suggested and has been basically accepted as the primary marker to define the InduanOienekian boundary; （3） a characteristic Lower Triassic excursion of carbon isotopes was brought to light and has been proven to be not only an excellent index for the stratigraphic correlation but also a unique indication for the perturbation of ecological environments in the aftermath of the end-Permian mass extinction; （4） a magnetostratigraphic sequence is constituted with a certain biostratigraphic control in the low-latitude region and it presents an important correlation to the Boreal sequence; （5） a cyclostratigraphic study provides an alternative method to constrain the age of the chronostratigraphic units; and （6） a scheme of the Olenekian subdivision is recently suggested to define the boundary between the Smithian and Spathian Substages. In addition, Chaohu is also the type locality of the Chaohuan Stage, the upper stage of the Lower Triassic in the China Chronostratigraphic System.Thus, the Lower Triassic of Chaohu is not only a classic sequence in South China, but also a key reference sequence to the investigation of the corresponding stratigraphy and geological events over the world. The recent achievements are viewed here for an overall understanding of the sequence. Then the current situation of the Induan-Olenekian and Smithian-Spathian boundaries is discussed to provide a reference for later works.
基金the financial support of Russian FBR(No.18-05-00023A)。
文摘Information on latest early Olenekian(latest Smithian)ammonoids is available apparently from only seven regions of the world,including South Primorye.Latest Smithian evidences on this topic are recorded from the West SMID(abbreviation from the Russian name of the quarry:"Building Materials and Details"),East SMID and Golyj Cape areas in South Primorye.This provides additional information on systematic composition of latest Smithian ammonoid,as well as conodont and brachiopod assemblages from the recently identified Shimanskyites shimanskyi Zone,located between lower Olenekian Anasibirites nevolini Zone and upper Olenekian Tirolites subcassianus Zone.There are many common ammonoid species in the Shimanskyites shimanskyi Zone and the underlying Anasibirites nevolini Zone,e.g.,Prosphingitoides sp.,Arctoceras septentrionale(Diener),Churkites syskoi Zakharov et Shigeta,Submeekoceras?subhhydaspis(Kiparisova),Prionites markevichi Zakharov et Smyshlyaeva,?Anasibirites?simanenkoi Zakharov et Smyshlyaeva,Xenoceltites?subvariocostatus Zakharov et Smyshlyaeva,and Mianwaliites zimini Zakharov et Smyshlyaeva.The base of the Shimanskyites shimanskyi Zone,marked by a negativeδ13Corg excursion in the Kamenushka-2 Section by our previous study,coincides with the FO(first occurrence)of ammonoids Shimanskyites shimanskyi Zakharov et Smyshlyaeva and Glyptophiceras cf.sinuatum(Waagen)and conodont Hindeodella budurovi Buryi.This zone is characterized additionally by some fossils common for the overlying upper Olenekian Tirolites subcassianus Zone:ammonoids of the genus Kamenushkaites,brachiopods Bittnerihyris margaritovi(Bittner)and Lepismatina sp.and conodont?Neogondolella?(=?Borinella)jubata Sweet.The latest Smithian ammonoids recorded from the Shimanskyites shimanskyi Zone totally consist of 30 taxa belonging to 11 families(Sageceratidae,Ussuiriidae,Aspenitidae,Paranannitidae,Arctoceratidae,Proptychitidae,?Galfetitidae,Prionitidae,?Kashmiritidae,Xenoceltitidae and Palaeophyllitidae).The problems of global correlation of uppermost Smithian strata are also discussed.
