The taxonomy and biostratigraphy of the Talicypridea-Cypridea-Nanxiongium ostracod fauna from the Nanxiong Group in the Nanxiong Basin is of great importance for the subdivision and correlation of the Upper Cretaceous non-marine strata in China. Abundant ostracods have been recovered in 270 samples from the Zhutian and Zhenshui formations, the upper part of the Nanxiong Group. There are 99 species in 23 genera (including 2 subge- nera) figured herein, including 12 new species herein described. This ostracod fauna is dominated by species of the four genera: Talicypridea, Cypridea, Nanxiongium, Candoniella. This ostracod fauna has also been reported from the Upper Cretaceous strata in Mongolia.
The ostracods of Late Cretaceous Wujia Formation and Palaeocene Shangyang Formation are found from 18 samples of 8 boreholes in the Hepu Basin,Guangxi.Twenty three species in 14 genera are figured here,including one new species.The ostracod fauna is subdivided into two distinct assemblages:1)Rhombicypridea quadrata-Heterocypris hepuensis-Limnocythere sinuata assemblage from the Wujia Formation,belonging to Talicypridea fauna of the Late Cretaceous;2)Sinocypris excelsa-Cypris concina-Parailyocypris changzhouensis assemblage from the Shang-yang Formation,belonging to Sinocypris fauna of the Palaeocene.Of great interest is the discovery of the boundary strata between the continous non-marine Cretaceous and Palaeogene of China.
This study is based on 725 ostracod samples systematically collected from eight profiles of the Upper Cretaceous—Palaeogene Luofozhai Group at Pingling,Wutaigang,Luofozhai,south to Nanxiong town,Fengmenao,Xiuren,Huangmaoping and Nuanshuitang in Nanxiong of Guangdong Province,Southern China.78 ostracod species(including two new species)in 21 genara are described from the Luofozhai Group.Two ostracod faunas and five zones are recognized in ascending order:the latest Cretaceous Porpocypris fauna(subdivided into P.globra and P.sphaeroidalis zones)and the Palaeocene Cypris-Sinocypris fauna(subdivided into Cypris concina,Sinocypris excelsa and Cyprois reniformis zones,corresponding to the Early,Middle and Late Palaeocene).
Twenty three species of 9 genera of ostracods were found in the Lingcha area of the Hengyang Basin,Hunan Province. Among them,Paleogene Cypris and Limnocythere are most abundant. Two ostracod biozones are recognized:the lower zone Cypris henanensis-Cyprois reniformis-Limnocythere honggangensis in the Limuping Formation and the upper one Limnocythere irregularis-Cy-pris favosa-Ilyocypris gaoyouensis in the Lingcha Formation. The ostracod faunas of the Limuping and Lingcha formations are similar to those of the Baoyue and Huayong formations of the Pearl River delta region respectively. This would suggest a late Paleocene age for the Limuping Formation and an early Eocene age for the Lingcha Formation. These suggestions are consistent with the results of mammal fauna,paleogeomagnetism and carbon-oxygen isotopes from the Limuping and Lingcha formations.
Recently an important advance has been made in the study of dinosaurs and fossil eggs of the Heyuan Basin. Oviraptorid dinosaur ( Heyuannia huangi Lu )was found in Doyuan County, and more than 10000 of fossil eggs ( belong to 4 genera and 4 species at least ) were collected.The ogg-bearing strata may be divided into two beds, the lower characterized by Spheroolithus-type and Dendroolithus-type eggs and the upper is dominated by Elongatoolithus-type eggs. Weld volcanic breccia was newly found in the north part of the basin. The lithostratigraphic sequence ( the Xiantang, Dongyuan, Gaopugang and Xinzhuangcun formations ) of the Heyuan Basin is established and may be correlated between the basin and Nanxiong, Danxia, and other basins of Guangdong.
The red beds of the northern Heyuan Basin (Guangdong Province, China) are more than 4,000 m thick. Based on the lithological characters, in ascending order these beds are divided into the Dafeng Formation, Zhutian Formation, and Zhenshui Formation of the Nanxiong Group, Shanghu Formation and Danxia Formation. The Nanxiong Group with relatively mature coarse clastic rocks attains about 2,940 m in thickness. The Dafeng Formation is 837 m thick, consisting of conglomerates and sandy conglomerates; the Zhutian Formation, which is 1,200 m thick, consists of purplish red sandstone with gravels, poorly sorted sandstone, feldspathic quartzose sandstone banded granular conglomerate, siltstone, and sandy mudstone. The Zhutian Formation is rich in calcareous concretions. Heyuannia (Oviraptoridae) and turtle fossils were found in this formation. The Zhenshui Formation deposited to a thickness of 900 m consists of coarse sediments, including granular conglomerate, and gravelly sandstone with well developed cross-beddings; the Shanghu Formation, which is 820 m thick, consists of purplish red granular conglomerate coarse sandstone intercalated with fine siltstone; the Danxia Formation characterized by the Danxia landform is composed of coarse clastic gravels and sandy gravels. The lower part of the Nanxiong Group whence dinosaur eggs and derived oviraptorosaurs come, belongs to the Late Cretaceous. No fossils are found in the Shanghu Formation or the Danxia Formation, but their stratigraphic order of superposition on the Nanxiong Group clearly shows their younger age.
Shanghudong and Wutaigang are typical areas responsible for the name Shanghu Formation, where abundant mammal fossils occur. Although the Early and Middle Paleocene mammal fauna was studied in detail long ago, the microfossils in this area have not been reported till now. In recent years, a lot of ostracods, gastropodas and charophytes were found from the Upper Member of Zhenshui Formation to the Lower Member of Shanghu Formation within the Wutaigang section. These ostracods belong to the Porpocypris assemblage and can be subdivided into the Porpocypris orbiculata zone and the P. sphaeroidalis zone. The first occurrence of the P. sphaeroidalis zone almost coincides with that of the Bemalambda zone. The authors suggest that the first occurrence of P. sphaeroidalis limits the bottom boundary of Paleocene, and hence the E/K boundary should lie between the P. sphaeroidalis zone and the P. orbiculata zone.
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