Trilobites From The Amphoton Deois Zone Of The Changhia Formation (Cambrian,Drumian) In Weifang,Shandong Province And Its Geological Significances

In order to supplement paleontological information of complete A mphoton deois zone in the Tanlu fault zone,perfect its trilobites association and biological characteristics in Amphoton deois zone,and achieve stratigraphic correlation of Amphoton deois zone and paleogeography of "Chron" on the basis of the previous study of stratigraphy in Changhia Formation and paleogeography in Changhia Period in Shandong Province.In this paper,complete Amphoton deois zone of Changhia Formation at Weifang,Shandong Province,which located at the west side of western Tanlu fault zone,was selected as research area to study Amphoton deois zone in Shandong Province with methods of collecting trilobite fossils layer by layer,compareing with the international stratigraphic units,and comparing of lithological characteristics and trilobite distribution characteristics in Amphoton deois zone in Wudangshan with that of other Amphoton deois zone in 7 typical section Cambrian in Shandong Province.Therefore,it is considered that this area belongs to Drumian Stage(Cambrian,Series 3),and its trilobite fossils are abundant,including:Ammagnostus laiwuensis(Lorenz,1906),Amphoton deois(Walcott,1905),Anomocarella albion Walcott,1905,Baltagnostus yaojiayuensis Yuan et al.,2012,Dorypyge richthofeni Dames,1883,Fuchouia manchuriensis(Walcott,1911),Grandioculus sp.,Hypagnostus parvifrons(Linnarsson,1869),Maotunia distincta(Resser et Endo,1937),Mapania striata Resser et Endo in Kobayashi,1935,M.(Mapanella)blackwelderi(Resser et Endo,1 937),Mapanopsis expansus Chang,1963,Parayujinia sp.,Solenoparia intermedia(Walcott,1906),Szeaspis centronatus(Resser et Endo,1937),and basically the same as the trilobite associations of Amphoton deois Zone in other Shandong Province.In terms of biological association,the layers 2,14,16 and 17 contain the greatest number of species,the layers 32,34 and 35 are poor in trilobites,the layers 3,26,29,31 and 33 have no trilobite,the layers 2,16,17 contain the richest Polymerid trilobites,and the 14th layer has the richest Agnostids.In addition,Amphoton deois zone is concentrated in Panchegou section of Changhia Formation in the west Shandong Province stratigraphic subregion.It is located at the lower part of the Panchegou section in Weifang-Linyi sub-areas,at upper,middle,and lower parts of Panchegou section in Zibo-Xintai sub-areas,and at upper limestone section of Changhia Formation in Jinan-Tengzhou sub-areas.What's more,based on the previous researchs of palaeogeography in the Changhia Period of Shandong Province,this paper further discussed the conclusion that there are Shoals facies and Intertidal seas facies in Shandong Province and getting deeper from west to east,representing an overall sedimentary environment of the water depth in east and shallow in west in "Amphoton deois Chron".Meanwhile,Zaozhuang area in the southern part of Shandong Province develops shoal facies,the water is shallow and has no Agnostid,therefore,it is speculated that the area may be an underwater uplift in the open platform in"Amphoton deois Chron".