LETHAIA REVIEW Palaeogene marine stratigraphy in China XIAOQIAO WAN, TIAN JIANG, YIYI ZHANG, DANGPENG XI AND GUOBIAO LI Wan, X., Jiang, T., Zhang, Y., Xi, D. & Li G. 2014: Palaeogene marine stratigraphy in China. Lethaia, Vol. 47, pp. 297–308. Palaeogene deposits are widespread in China and are potential sequences for locating stage boundaries. Most strata are non-marine origin, but marine sediments are well exposed in Tibet, the Tarim Basin of Xinjiang, and the continental margin of East China Sea. Among them, the Tibetan Tethys can be recognized as a dominant marine area, including the Indian-margin strata of the northern Tethys Himalaya and Asian- margin strata of the Gangdese forearc basin. Continuous sequences are preserved in the Gamba–Tingri Basin of the north margin of the Indian Plate, where the Palaeogene sequence is divided into the Jidula, Zongpu, Zhepure and Zongpubei formations. Here, the marine sequence ranges from Danian to middle Priabonian (66–35 ma), and the stage boundaries are identified mostly by larger foraminiferal assemblages. The Paleocene/Eocene boundary is found between the Zongpu and Zhepure forma- tions. The uppermost marine beds are from the top of the Zongpubei Formation (~35 ma), marking the end of Indian and Asian collision. In addition, the marine beds crop out along both sides of the Yarlong Zangbo Suture, where they show a deeper marine facies, yielding rich radiolarian fossils of Paleocene and Eocene. The Tarim Basin of Xinjiang is another important area of marine deposition. Here, marine Palae- ogene strata are well exposed in the Southwest Tarim Depression and Kuqa Depres- sion. They comprise mostly neritic and coastal lagoon facies of the Tethyan realm. Palaeontological evidence suggests that the Paleocene/Eocene boundary here is in middle of the Qimugen Formation. The Tarim Basin was largely drained by Late Oligocene. To the east, the marine offshore Palaeogene strata are widespread in the North Taiwan and East Zhejiang depressions of the continental shelf basin of East China Sea. Abundant fossils including foraminifera, calcareous nannofossils, ostrac- ods, pollen and bivalves occur in the marine environment. Biostratigraphically, the sequence is well correlated with the international planktonic foraminiferal and nannofossil zonations. □ Biostratigraphy, East China Sea, marine Palaeogene, Tarim Basin, Tethys Himalaya. Xiaoqiao Wan [[email protected]], Tian Jiang [[email protected]], Yiyi Zhang [[email protected]], Dangpeng Xi [[email protected]], and Guobiao Li [liguobiao@ cugb.edu.cn], State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Xueyuan Lu, 29, Beijing 100083, China; manuscript received on 11/10/2013; manuscript accepted on 09/12/2013. The Palaeogene is an important interval of geological non-marine sections as well as marine sediments, history, when the climate changed from ‘green which are well exposed in southern Tibet, in the house’ to ‘ice house’. Several other significant geo- southwestern Tarim Basin of Xinjiang Region, and logical events occurred during this time, and each of on the continental shelf basin of the East China Sea them is marked by a significant change in the (Fig. 1). Among these, the Tethys Himalaya is a stratigraphical record. Accurate descriptions of the dominant marine area where continuous Palaeogene Chinese deposits provide opportunities for correla- successions are preserved and accessible as GSSP tion with the international chronostratigraphical candidates or as auxiliary boundary stratotypes. The framework for the Palaeogene System. Several Global southwestern Tarim Basin was a gulf of East Tethys Standard Stratotype-section and Points (GSSP) have with shallow marine and intercalations of terrestrial already been defined for the Palaeogene, but GSSP’s sediments. The continental shelf basin of the East are still missing for Bartonian, Priabonian and Chat- China Sea preserves a large group of almost continu- tian. The International Subcommission on Palaeo- ous marine deposits of Palaeogene. This paper reviews gene Stratigraphy encourages the study of reference the occurrence of marine Palaeogene strata in China, sections for stage transitions also outside the based mostly on the authors’ original research pub- sedimentary basins that have traditionally been used lished in the Chinese literature, often in Chinese. This for stage definitions. This study presents such a review represents a contribution for extending non-traditional area analysis. In addition, China international knowledge on the Palaeogene that is represents an opportunity to study Palaeogene outside the well-known and traditional areas. DOI 10.1111/let.12071 © 2014 Lethaia Foundation. Published by John Wiley & Sons Ltd 298 Wan et al. LETHAIA 47 (2014) 0 500km Harbin . .. Urumqi II Beijing Xi’an I Lhasa Wuhan Shanghai Chongqing III Sea Guiyang Land Kunming Guangzhou River and Lake Salt or Brackish Lake Intermountain basin Fig. 1. Sketch map showing the occurrence of marine Palaeogene strata in China. I, Tethys Himalaya. II, Southwestern Tarim Basin. III, continental shelf basin of East China Sea. et al. 2005). Marine deposition ceased by latest Palaeogene in Tethys Himalaya Eocene during Himalayan orogenesis. On the north margin of the Indian Plate, marine Southern Tibet was a part of the Tethys-Himala- Palaeogene is well exposed in the Gamba–Tingri yan Sea, in which a variety of carbonate and neri- Basin and Saga–Gyangze belt (Wan 1987, 1990, tic clastic sediments accumulated. The marine 1991; Ding et al. 2005). Marine Palaeogene on Palaeogene sedimentary sequences occur both the Asian-margin occurs mostly along the Zanda– south and north of the Yarlung Zangbo suture in Zhongba belt (Fig. 2). southern and central Tibet. They consist of Indian-margin strata of the northern Tethys Hima- Marine Palaeogene in Gamba–Tingri Basin of laya, and Asian-margin strata of the Gangdese north margin of Indian Plate forearc basin. They are subdivided in a north– south direction into a number of tectonostrati- The Gamba Zhongpu is the type section in the graphical units, generally separated by major Gamba–Tingri Basin (Fig. 3). The succession is thrusts or normal faults (Wan et al. 2002; Ding described in ascending order, as follows. Tibet China Lhasa Zhongba III Yarlung-ZangboYarlungZangboSuture suture Lhasa Xigaze Saga II Gyangze I Tingri Gamba Mt.Everest 1 2 3 4 0 150km Fig. 2. Palaeogene geography of southern Tibet. 1, marine sediments; 2, non-marine sediments; 3, Gangdis^e magmatic arc; 4, Ophiolite belt; I, Gamba–Tingri Basin; II, Saga–Gyangze belt; III, Zanda–Zhongba belt. LETHAIA 47 (2014) Marine Palaeogene in China 299 Zongpub ei Formation Zhepure For mation Zo ngpuFormation JidulaFormation Fig. 3. Paleocene–Eocene Zongpu section in Gamba, southern Tibet. The Jidula Formation (177 m) is a marine indicating that they are enriched in organic sequence dominated by yellowish white, indu- carbon. rated, homogeneous sandstone, in which sandy • Member 3 a dark grey nodular limestone, of limestone beds are intercalated in the middle and wackestone and packstone composition, which in upper part of the formation. The exposure sur- its uppermost 59 cm becomes a grey thick-bedded face at the base of the formation is overlain by a limestone breccia incorporating several thin layers 2- to 5-cm-thick yellowish grey clay bed contain- of marl that lack larger benthic foraminifera. This ing dispersed gravel. Foraminifera such as Rotalia marly bed was considered in the field to define an hensoni, Rotalia dukharni, Smoutina cruysi and erosional surface. A larger foraminiferal fauna Lockhartia haimei are found in this clayey bed. in member 3 is characterized by a Miscellanea- The foraminifera are in situ as they are Palaeo- Daviesina-Operculina assemblage, providing a gene elements, avoiding the possibility reworked Seladian–Thanetian age for this formation. The from underneath Cretaceous strata. Ostracods Paleocene/Eocene boundary is between the Zon- and algae were found in limestone intercalations gpu and Zhepure formations (Wan et al. 2010). in the middle part of the formation. Collectively, the micro-fauna indicates a Danian age for the The overlying Zhepure Formation (50 m) is a grey, formation. massive and thick-bedded Alveolina packstone, with The overlying Zongpu Formation (223 m) con- limestone beds separated by shaly intercalations sists of massive limestone (dolomitized in the lower 2–10 cm thick. This formation forms a prominent section), nodular limestone and minor amounts of ridge halfway up the northern flank of the Zongpu calcareous marlstone and marl. In the field, we sub- valley. It has a distinctive composition, characterized divided this formation into three members, which by masses of Alveolina, sporadically interspersed from the bottom to the top are: with Orbitolites. The original ‘Zhepure Formation’ • Member 1, a medium-bedded dark grey, partly (Xu et al. 1989; Wan 1990) was composed of the dolomitic nodular packstone containing common current formation and its overlying shaly beds. Its dasycladacean algae, debris of Halimeda. The massive and thick-bedded texture is different from foraminifera in this member belong to a Rotalia- that of shaly beds above and most nodular limestone Lockhartia assemblage. in the underlying Zhongpu Formation. We describe • Member 2, a dark grey to blackish thickly bedded this interval as an independent formation, of Ypre- limestone sequence comprised of intercalated sian to Bartonian (Eocene) age. thick, dark-coloured