Biostratigraphy Of Oryctocephalid Trilobites From The Cambrian "Tsinghsutung Formation" At Balang Village, Jianhe County, Guizhou Province

Cambrian Series 2 and 3 in Balang, Jianhe area was deposited in transitional slope belt, the “Tsinghsutung Formation”(Cambrian Series 2) exposed in this area is 272 m thick. The lower part of the formation is dominated by gray, dark grayish limestone; the mid-upper part is composed of light gray thin-bedded limestone in tercalatedgray, yellow-greenish mudstone, near top part is consisted of dark grey medium-bedded dolomite in. Its lithologic chracters is distinct from the typical Tsinghsutung Formation in Western and Northern Guizhou and also different from the coeval Wuxun Formation in Danzhai area, so we temporarily use “Tsinghsutung Formation” instead of disparity. A new Burgess Shale-type lagerst?tte was discovered in the mid-upper part of the “Tsinghsutung Formation” at Balang village, which has been named as Jianhe Biota, in the fossil asemblege, including abundant trilobit es, and they distribute in many layes of the entire formation. besides, also including representatives of Ptychopriidae and Redlichiidae. Oryctocaridae is consisted of 5 species attributing 2 genera and1 subgenus, Protoryctocephalus balangensis Zhao et Yuan in Yuan et al., 2002; Protoryctocephalus elongatus Zhao et Yuan in Yuan et al., 2002; Protoryctocephalus arcticus Geyer et Peel, 2011; Duyunaspis duyunensis Chang et Chien 1977 and Arthricocephalus(Arthricocephalites) jishouensi s Zhou in Zhou et al., 1977. The first appearance data(FADs) of Duyunaspis duyunensis and Arthricocephalus(Arthricocephalites) jishouensis appeared in under lying the Balang Formation. Protoryctocephalus balangensis and Protoryctocephalus elongatus first appear in the “Tsinghsutung Formation” and range to the lower part of overlying Kaili Formation. Protoryctocephalus arcticus was described by Geyer and Peel in 2011 based on a cephalon specimen from the Henson Gletscher Formation in Peary Land area of northern Greenland. thisspecies firstly appear in the lower part of the “Tsinghsutung Formation”, ranging 104 m interval from 135 m to 239 m away from the the formation. Based on a great number of specimens collected from the interval, the Protoryctocephalus arcticus Zone was established. However, this species have not been discovered in the lower part of the formation. The Protoryctocephalus arcticus Zone is only limited to the middle and upper parts of the “Tsinghsutung Formation” at Balang village. More field work in the lower part of the formation is required to verify the validity of this biozone. The Protoryctocephalus arcticus Zone can be correlated with the Eoagostus roddyi-Arthricocephalus chauveaui Zone in the lower part of the Henson Gletscher Formation in north Greenland. According to Redlichia(R.) guizhouensis and Redlichia(R.) nobilis occurring in the middle and upper parts of the “Tsinghsutung Formation” at Balang, the Protoryctocephalus arcticus Zone can be correlated with the upper part of the classical Tsinghsutung Formation in northern Guizhou.Previously, biostratigraphic framework had been established by Yuan Jin- liang in the Tsinghsutung Formation, that is, Arthricocephalus jishouensis-Changaspi s plana Assemblage Zone from the lower part of the Tsinghsutung Formation and upper Protoryctocephalus wuxunensi s Zone from the upper part of the Tsinghsutung Formation, which includes the local “Tsinghsutung Formation”. However, the two biozones have not been recognized in the “Tsinghsutung Formation” at Balang. The new Protoryctocephalus arcticus Zone for the “Tsinghsutung Formation” of Balang provides new Criterion for revising Oryctocephalid trilobite zones in this area, and evidence for further biostratigraphic correlation in the world.