The Late Caledonian to Early Hercynian North Qilian orogenic belt in no rthwestern China is an elongate tectonic unit situated between the North China p late in the north and the Qaidam plate in the south. North Qili...The Late Caledonian to Early Hercynian North Qilian orogenic belt in no rthwestern China is an elongate tectonic unit situated between the North China p late in the north and the Qaidam plate in the south. North Qilian started in the latest Proterozoic to Cambrian as a rift basin on the southern margin of North China, and evolved later to an archipelagic ocean and active continental margin during the Ordovician and a foreland basin from Silurian to the Early and Middle Devonian. The Early Silurian flysch and submarine alluvial fan, the Middle to L ate Silurian shallow marine to tidal flat deposits and the Early and Middle Devo nian terrestrial molasse are developed along the corridor Nanshan. The shallowin g upward succession from subabyssal flysch, shallow marine, tidal flat to terre strial molasse and its gradually narrowed regional distribution demonstrate that the foreland basin experienced the transition from flysch stage to molasse stag e during the Silurian and Devonian time.展开更多
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
基金TheresearchissponsoredbytheNationalNaturalScienceFoundationofChina (No .4 9972 0 78)
文摘The Late Caledonian to Early Hercynian North Qilian orogenic belt in no rthwestern China is an elongate tectonic unit situated between the North China p late in the north and the Qaidam plate in the south. North Qilian started in the latest Proterozoic to Cambrian as a rift basin on the southern margin of North China, and evolved later to an archipelagic ocean and active continental margin during the Ordovician and a foreland basin from Silurian to the Early and Middle Devonian. The Early Silurian flysch and submarine alluvial fan, the Middle to L ate Silurian shallow marine to tidal flat deposits and the Early and Middle Devo nian terrestrial molasse are developed along the corridor Nanshan. The shallowin g upward succession from subabyssal flysch, shallow marine, tidal flat to terre strial molasse and its gradually narrowed regional distribution demonstrate that the foreland basin experienced the transition from flysch stage to molasse stag e during the Silurian and Devonian time.
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.
