The Cambrian paleogeography in south Ch ina can be divided into Yangtze platform, platform margin slope (including upper slo pe and lower slope) and basin. The carbonate gravity deposits are well developed there, pa...The Cambrian paleogeography in south Ch ina can be divided into Yangtze platform, platform margin slope (including upper slo pe and lower slope) and basin. The carbonate gravity deposits are well developed there, particularly in the Yangtze platform adjacent areas. This paper mainly d eals with declivity fan characters of the Chefu age in Fenghuang adjacent areas, western Hunan Province. According to their distribution and thickness, three ma in declivity fans have been divided in the study areas, namely, Dama (∈c dsf), Machong (∈c msf) and Huangheyuan (∈c hsf) declivity fans. Each fan's charac ters are described in detail in this paper. Based on their distribution range, s cale and fossiliferous layers, two peak periods (fair developmental period) are distinguished: (1) Linguagnostus reconditus Zone (time), and (2) Glyptagno stus reticulatus Zone (time). They were characterized by huge thick limestone breccia layers (single layer 3-4 m thick) and closely spaced spread. Besides, th ere are also two developmental periods: (1) Lejopyge laevigata Proagnostus b ulbus Zone (time), and (2) Agnostus inexpectans Proceratopyge protracta Z one (time) to Erixanium Zone (time) to Corynexochus plumula Sinoprocerato pyge cf. kiangshanensis Zone (time), while Glyptagnostus stolidotus Zo ne (time) was an interstitial period (without or rare limestone breccias). All t hese features may verify the relative movement of the earth crust and paleoclima te variety of the Chefu age in the study areas.展开更多
Middle and Late Cambrian trilobite faunas from the Dama section in western Hunanare are composed of 63 genera and subgenera, 84 species, and two forms of gen. et sp. indetermined. Which include a mixture of cosmopolit...Middle and Late Cambrian trilobite faunas from the Dama section in western Hunanare are composed of 63 genera and subgenera, 84 species, and two forms of gen. et sp. indetermined. Which include a mixture of cosmopolitan agnostoids and polymeroids. Three new species,Hardyoides damaensis,Meringaspis damaensis and Rhyssometopus (Rodtrifinis) nitidus, are described by present author in 2004. Besides, Erixanium is recognised for the first time in study area, which is significant for biostratigraphical correlation of the Late Cambrian in the Austalo-Asia region. According to distribution regularity vertical, the Middle and Late Cambrian trilobites can be divided into 9 trilobite communities for the Dama section. Based on the trilobite communities analysis, the author concludes that from the east Mt. Lailong to Dama through Fenghuang, further east, reach in Chenxi,the palaeoenvironments were changed from a shallow-water of oxygen-rich (platform margin slope ) into a deep-water of oxygen-poor setting (basin).展开更多
文摘The Cambrian paleogeography in south Ch ina can be divided into Yangtze platform, platform margin slope (including upper slo pe and lower slope) and basin. The carbonate gravity deposits are well developed there, particularly in the Yangtze platform adjacent areas. This paper mainly d eals with declivity fan characters of the Chefu age in Fenghuang adjacent areas, western Hunan Province. According to their distribution and thickness, three ma in declivity fans have been divided in the study areas, namely, Dama (∈c dsf), Machong (∈c msf) and Huangheyuan (∈c hsf) declivity fans. Each fan's charac ters are described in detail in this paper. Based on their distribution range, s cale and fossiliferous layers, two peak periods (fair developmental period) are distinguished: (1) Linguagnostus reconditus Zone (time), and (2) Glyptagno stus reticulatus Zone (time). They were characterized by huge thick limestone breccia layers (single layer 3-4 m thick) and closely spaced spread. Besides, th ere are also two developmental periods: (1) Lejopyge laevigata Proagnostus b ulbus Zone (time), and (2) Agnostus inexpectans Proceratopyge protracta Z one (time) to Erixanium Zone (time) to Corynexochus plumula Sinoprocerato pyge cf. kiangshanensis Zone (time), while Glyptagnostus stolidotus Zo ne (time) was an interstitial period (without or rare limestone breccias). All t hese features may verify the relative movement of the earth crust and paleoclima te variety of the Chefu age in the study areas.
文摘Middle and Late Cambrian trilobite faunas from the Dama section in western Hunanare are composed of 63 genera and subgenera, 84 species, and two forms of gen. et sp. indetermined. Which include a mixture of cosmopolitan agnostoids and polymeroids. Three new species,Hardyoides damaensis,Meringaspis damaensis and Rhyssometopus (Rodtrifinis) nitidus, are described by present author in 2004. Besides, Erixanium is recognised for the first time in study area, which is significant for biostratigraphical correlation of the Late Cambrian in the Austalo-Asia region. According to distribution regularity vertical, the Middle and Late Cambrian trilobites can be divided into 9 trilobite communities for the Dama section. Based on the trilobite communities analysis, the author concludes that from the east Mt. Lailong to Dama through Fenghuang, further east, reach in Chenxi,the palaeoenvironments were changed from a shallow-water of oxygen-rich (platform margin slope ) into a deep-water of oxygen-poor setting (basin).
