Through the research of the research group (Wang Yuanqing, Li Xi, Tong Yongsheng, etc. ), the main progress at present is as follows: (1) Candidate profiles of continental stratotype and boundary stratotype have been preliminarily selected; Abundant mammalian fossils have been discovered and accumulated, and preliminary biota analysis and regional comparison have been made.
(1) Location of Lushi stratotype and boundary layer profile
The candidate stratotype profile of Lushi period was initially determined in Yuhuangding-Qiliyingxi-Shimiao profile of Liguanqiao basin at the junction of Hubei and Henan. The candidate section of boundary stratotype is selected from the Da 'ao-Pangwan section near Qingtangling, Xijiadian Town, danjiangkou city City, Hubei Province (Figure 107).
Figure 107 Schematic diagram of candidate profiles and strata distribution of Lushi stratotype and boundary layer type.
(2) Description of Lushi stratum profile and boundary stratum profile.
1. Lushi layered profile description (Yuhuangding Shimiao profile)
The Lushi Formation in this section is 2258 meters thick, including the upper part of Yuhuangding Formation, Dacangfang Formation and Hetaoyuan Formation.
Progress and Achievements of Major Dating Strata Research Projects in China (200 1 ~ 2009)
Progress and Achievements of Major Dating Strata Research Projects in China (200 1 ~ 2009)
The underlying Cambrian gray and dark gray argillaceous banded crystalline limestone.
2. Lushi boundary stratotype profile (Daao Pangwan profile in Xijiadian Town, Danjiangkou, Hubei Province)
The Yuhuangding Formation and Dacangfang Formation of the Lower Lushi stage are continuously deposited in this section, but the upper Lushi stage stratum (Hetaoyuan Formation) is missing, and Dacangfang Formation is covered by the pseudo-conformity of the Upper Tertiary stratum. Neogene conglomerate in overlying strata
Progress and Achievements of Major Dating Strata Research Projects in China (200 1 ~ 2009)
Progress and Achievements of Major Dating Strata Research Projects in China (200 1 ~ 2009)
The underlying Cambrian dark gray argillaceous banded limestone.
(3) Lushi biostratigraphic sequence
At present, the main fossils found in the strata equivalent to Lushi stage are mammals, followed by ostracods. As far as the distribution of mammalian fossils is concerned, the Lushi period in Liguanqiao Basin consists of three layers of mammal fauna from bottom to top: ① Zhanggou fauna at the bottom (located in the east of Zhanggou Village, Huangying Township, Danjiangkou, Hubei Province), which is characterized by the predominance of rodents (57. 65438 0%) and some ancient types of high content (42. 9%). The main genera and species are: Acanthopanax progressive, Acanthopanax. ，Gobiatherium minutus，Lophialetes？ Primula in Yimeng Mountain. ，Forstercooperia？ Species éomer Ropes? ② The second fauna comes from the upper stratum of Dacangfang Formation, and the fossils are not completely preserved. * * There are 6 categories: Sciuravidae indet. Genus and species of Ancuropodidae. The Oribatidae in ancient Lei Shou. Genus and species of odontidae in China. Genus and species of Chiropteridae? Is the species undecided? Basilidae. (Wang Jingwen, 1988), a young rhinoceros with a new ridge? Caenolophus？ ③ The third fauna comes from the lower part of the Walnut Garden Formation in Beishipigou, taoyuan village, Xichuan, Henan Province, with high abundance and diversity, reaching 46 species in 22 families. Its main genera and species are: sparganosis, Chlamys farreri, and the first family. Are the genera and species uncertain? Institute of archaeology. , Dendrolimus punctatus, Shiqian Nostoc flagelliforme, Lushi Nostoc flagelliforme, Danjiang Lushi Rabbit? Lucillagus? Danjiang rabbit, desert rabbit (undetermined species) Shamolagus sp., elegant bimodal rabbit Portunus erywart, rat family? Echinococcus, liguan Bridge Oriental Cylindrical Rat, Li Guan Bridge Oriental Cylindrical Rat, True Rat (undetermined) See Pareumys sp., Myxomys. , Eriocheir sinensis, Eriocheir sinensis, Eriocheir sinensis, Eriocheir sinensis, Eriocheir sinensis, Eriocheir brandti, Eriocheir brandti, Epinephelus brandti, Epinephelus brandti, Eriocheir sinensis, Eriocheir sinensis. Trapezius muscle, moon muscle, protopterosaur. , protopterosaur species. , Shipigou? Stone-skinned salamander, small-headed salamander, small iguana, casto East, Henan meat cleaver? Henan, Lushi, Xichuan, Xichuan, Zhong Jian and Lei Shou (undetermined)? Species, LEPIDOPTERA tree shrews, walnut orchard tree shrews, small tree shrews, Danjiang tree shrews, Daishi tree shrews in Xichuan, Xu Shi tree shrews, Xiqiao rhinoceros (undetermined species), etc. Prodinoflagellate. (undetermined), Acanthoptera domestic animals, namely, Jiajianictis muricatus, Ardynictis zhaii and Diptera, belong to the family Acanthoptera.
According to the characteristics of mammalian fossils in Lushi period, there are two different fauna combinations in this period. The lower part is Ashantou-type mammal group, which is characterized by odd-hoofed animals accounting for a large proportion in the fauna, among which primitive tapirs are the majority, and tapirs endemic to Asia are the majority. In primitive tapirs, there are not only swamp tapirs, but also invertebrate tapirs. Misgurnus began to appear, and the gobies of Artiodactyla rarely appeared. In the combination, there are some common ancient ungulates, such as true dinosaur-type crown-toothed mammals, Evanta-type and Gobi-type horned mammals. Among the rodents in fauna, primitive comb-toed rodents endemic to Asia are the majority, and accessory rodents are occasionally seen.
The upper part of deer stone is a Ding Man-type mammal group, which is characterized by the fact that among ungulates, odontododactyl is still dominant, but the original types of amphibian rhinoceros and rhinoceros begin to appear, the number and species of swamp tapirs are obviously reduced, and tapirs and Dai tapirs are obviously differentiated; Lei Shou class is also a common combination; Bifidobacterium type, Gobi pig type and Carboniferous animal type appeared in cloven-hoofed animals. Among the ancient ungulates, the animals afraid of horns are similar to extinct animals; Crown-toothed mammals have been specialized; Rodents are mainly primitive comb-toed rodents, with primitive rodent-shaped suborder species, and rabbit-shaped rodents have been initially differentiated; In this fauna, cassava, Lei Shou, Central America and primitive comb-toed rodents reached their heyday.
(4) The definition of the bottom boundary of Lushi order and the identification characteristics of the order.
At present, due to the lack of continuity in the discovery of mammalian fossils, it is difficult to determine the bottom boundary of the terrestrial Lushi stage, and it is also difficult to determine the marker fossils of this stage and its first horizon. It needs to be solved by comprehensive research of various methods in the future.
However, according to the discovered mammalian fossils, the Lushi stage can be determined. In other words, there are abundant mammalian fossils in Lushi period, and quite a few genera and species emerged from Lushi period, which is unique to Lushi period. According to their existence, the approximate horizon of Lushi stage can be determined. These endemic mammals are: Iconapterodus, Sinosinopa, Neoryctes, Eodendrogale, Lushius, Lushila-gus, Strenulagus, Dituberolagus, Dawsonolagus, Asiomys, Orientocylindrodon, Tamquammys、Viriosomys、Tsinlingomys、Chuankueimys、Yuomys、Saykanomys、Stelmomys、Boromys、Zoyphiomys、Hydentomys、Pa-lasiomys、Raricricetodon、Primisminthus、 Hydentomys, mongoHarpagolestes, Lunania, Helaletes, Hyrachyus, Aktauchyus, Schlosseria, Lophialetes, Yimengia, Brevi -odon, Teleolophus, Telmatherium, Metatelmatherium，Desmatotitan，Hyotitan，Arctotitan，Acrotitan，Proti-tan，Microtitan，Dolichorhinoides，Gnathotitan，？ Tripod, emperor penguin, snail, goby, goby, etc.
(5) Regional comparison of Lushi stage.
According to the comparison of mammalian fossils, the lower strata of terrestrial stage can be compared with Bridgerian in North America, because they contain Mesonyx, Uintatherium, Thinocyon, Hyrachyus and Helatetes. Eomorpus, Foestercooperia, Triplopus and Harpagolestes, which are the same as the early strata in Ewintan, North America, appear in the upper layer of Lushi stage and can be compared.
In China, the lithostratigraphic units that are roughly in the same period as Lushi period are: the upper part of Wanghuangding Formation-Dacangfang Formation-Hetaoyuan Formation in Liguanqiao Basin at the junction of Hubei and Henan; Ashantou Formation and Yi 'er Ding Man Ha Formation in Erenhot, Inner Mongolia; Wulan Xire Formation in Siziwangqi area; Lushi Formation in Lushi Basin of Henan Province and Lizhuang Formation in Xinyang Area; Guanzhuang formation, Mengyin area, Shandong province; Fossil gully formation in Junggar basin, Xinjiang.