Introduction
Sediments of the coastal plains and the continental shelves record the dynamic history of the shoreline migration caused by the ~120 m sea-level changes during the Quaternary (Fleming et al., Reference Fleming, Johnston, Zwartz, Yokoyama, Lambeck and Chappell1998). Through regional micropaleontological and stratigraphic comparisons in the sedimentary cores from East China, four major marine transgressions have been recognized during the late Pleistocene. The last one, post-glacial “Ammonia transgression”, is the most notable and widespread along the coastline (Wang et al., Reference Wang, Min, Bian and Chen1981). Numerous boreholes have been drilled and studied in various parts of East China over the last several decades (Lin, Reference Lin1979; Wang and Min, Reference Wang and Min1979; Li et al., Reference Li, Bian and Wang1988; Zhu and Lin, Reference Zhu and Lin1990; Chen and Stanley, Reference Chen and Stanley1995; Stanley and Chen, Reference Stanley and Chen1996; Wang et al., Reference Wang, Yu, Tang, Zhao, Wang and Huang2002; Shu et al., Reference Shu, Xiao, Zhao, Zhang, Cheng and Li2010; Xiong et al., Reference Xiong, Hou, Li and Chen2010; Wang et al., Reference Wang, Zhuang, Saito, Chen, Zhan and Wang2012). However, introduction of old carbon and reworking resulted in less-reliable dates, which has hampered further study on the glacial-interglacial environmental changes in East China (Stanley and Chen, Reference Stanley and Chen2000).
Due to the lower last glacial sea level and excavation of previous marine sediments, the deeply incised Yangtze paleo-valley received a significant amount of post-glacial deposits, up to 80 m thick in this region (Li and Wang, Reference Li and Wang1998; Li et al., Reference Li, Chen, Zhang, Yang and Fan2000), which provides an excellent opportunity for reconstructing the post-glacial environmental changes in East China.
In this study, benthic foraminiferal assemblages are reported from three cores of the incised Yangtze paleo-valley. The foraminiferal fauna can be correlated with records of previous studies in the Yangtze Delta region. Based on reliable AMS 14C dates, the high-resolution foraminiferal data presented here provide new evidence for post-glacial variations in climate and depositional environments.
Geological setting
The Yangtze Delta has been developing in a sedimentary basin formed in association with the Quaternary neotectonic orogeny in East China (Guo et al., Reference Guo, Li, Xu, Li and Zhang1997; Wang et al., Reference Wang, Zhang, Li, Tao and Xie2008). The Quaternary stratigraphic sequence of the Yangtze Delta is up to 300 m thick, consisting of the Haimen Formation (lower Pleistocene), Qidong Formation (Middle Pleistocene), Kunshan Formation (MIS 5), Gehu Formation (MIS 3), and Rudong Formation (Holocene) (Wu and Li, Reference Wu and Li1987). The Rudong Formation is represented by fluvial, estuary, shallow marine, and deltaic facies, and can be divided into three members: the lower member is composed of gray silt and grayish black slit clay; the middle is composed of gray or grayish black silt, fine-grained sand, and slit clay; and the upper member is composed of grayish yellow clay, clayey silt, and gray silt (Wu and Li, Reference Wu and Li1987).
The Yangtze Delta can be subdivided into three units: the incised paleo-valley and the northern and southern flanks (Fig. 1; Li et al., Reference Li, Chen, Zhang, Yang and Fan2000). The incised paleo-valley is an area where the estuary migrated, which contains several subdeltas and estuary bars. With rising sea level, the post-glacial marine transgression resulted in filling the incised valley and formation of the river channel, floodplain-estuary, estuarine-shallow marine, and deltaic sedimentary facies (Li et al., Reference Li, Chen, Zhang, Yang and Fan2000). Since the middle Holocene, the delta has been developing mainly in the incised valley, prograding to the east and southeast (Li et al., Reference Li, Wang, Sun, Zhang and Fan2002; Wang et al., Reference Wang, Zhan, Long, Saito, Gao, Wu, Li and Zhao2013).
Figure 1 Location map showing the cores studied in the paleo-incised Yangtze Valley (range of paleo-incised Yangtze Valley after Li et al., Reference Li, Chen, Zhang, Yang and Fan2000).
Materials and methods
The upper 42.2 m, 86 m, and 67 m of deposits in cores ZKA4, LZK1, and CSJA6, respectively, comprise the Rudong Formation. The sedimentary sequence varies from gravelly sand, coarse-grained sand in the basal part, fining-upward to the main part of gray, grayish yellow, brown, or slate gray silt, silty clay, and clayey silt. Planar bedding, lenticular bedding, and micro-erosional surfaces are locally present (Fig. 2).
Figure 2 Variation of Lithology, benthic foraminiferal abundance, diversity, and H(s), planktonic foraminiferal content in the cores ZKA4, LZK1, and CSJA6, with reconstructed paleogeographic curve. Solid line represents BF abundance (/50 g); dashed line represents PF abundance (/50 g).
We analyzed 455 samples that were collected from the three cores at 10–50 cm intervals. All samples were air-dried and weighed, and soaked in water for one week. Diluted H2O2 (5%) was added to help disaggregate the indurated samples when needed. After the samples were washed through a 74μm sieve, the coarse fraction was oven dried at 60°C and stored for foraminiferal studies. All the foraminiferal specimens were picked, identified, and counted. The Shannon index (Hs) was calculated to evaluate the variation of benthic foraminiferal complex diversity (Shannon, Reference Shannon1948).
AMS 14C dating of Core ZKA4 and Core CSJA6 was performed on the plant debris, charcoal, or the whole sediments either at Beta Analytic Inc. or Peking University (Yu et al., Reference Yu, Hu, Yang, Zhang, Jiang, Ke and Lao2014; Ma et al., Reference Ma, Yu, Jiang, Zhang, Lao, Zhao and Wei2015; Table 1).
Table 1 AMS 14C dates of Core ZKA4 and CSJA6 (Yu et al., Reference Yu, Hu, Yang, Zhang, Jiang, Ke and Lao2014; Ma et al., Reference Ma, Yu, Jiang, Zhang, Lao, Zhao and Wei2015).
Repositories and institutional abbreviations
All cores examined in this study are from the paleo-valley of the Yangtze Delta, including one core from Shanghai (LZK1) and the other two from Jiangsu Province (ZKA4 and CSJA6; Fig. 1). Core LZK1 (31°20′N, 121°50′E) is just 0.25 m above the China National Vertical Datum (CNVD, 1985); cores ZKA4 (32°22′N, 119°37′E) and CSJA6 (32°05′N, 121°17′E) are 6 m and 4 m above the CNVD, respectively. All described specimens are housed at the Nanjing Institute of Geology and Palaeontology (NIGP), Chinese Academy of Science. Referred type specimens are housed at the National Museum of Natural History, Smithsonian Institution, Washington, D.C. (USNM), CC=Cushman collection; MO=mollusk collection; The Natural History Museum, London (BMNH), HA=Heron-Allen slide collection, ZF=Zoology: Foraminifera; Geological Museum, Louisiana State University, Baton Rouge, Louisiana (LSUGM); and Tongji University, Shanghai (TJU), H=Hai (Marine in phonetics Chinese).
Systematic paleontology
The classification of the order Foraminiferida follows that given by He et al. (Reference He, Hu and Wang1965), Wang et al. (Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988), and Loeblich and Tappen (Reference Loeblich and Tappen1988).
Order Foraminiferida Eichwald, Reference Eichwald1830
Suborder Miliolina Delage and Hérouard, Reference Delage and Hérouard1896
Family Miliolidae Ehrenberg, Reference Ehrenberg1839
Genus Quinqueloculina d’Orbigny, Reference d’Orbigny1826
Quinqueloculina lamarckiana d’Orbigny, Reference d’Orbigny1839a
Figure 3 SEM photos of the foraminifers from Core CSJA6, Nantong, Jiangsu and Core LZK1, Hengsha Island, Shanghai. All scale bars are 100 μm. (1–3) Quinqueloculina lamarckiana: (1a) front view, CSJA6, depth 33.8–33.9 m, Reg. No. K2–036; (1b) apertural view, CSJA6, depth 33.8–33.9 m, Reg. No. K2–036; (2) rear view, LZK1, depth 31.9–32.0 m, Reg. No. K2–033; (3) front view, LZK1, depth 31.5–31.6 m, Reg. No. K2–032. (4–6) Quinqueloculina venusta: (4) front view, CSJA6, depth 33.8–33.9 m, Reg. No. K3–004; (5) apertural view, CSJA6, depth 47.6–47.7 m, Reg. No. K3–006 (6) rear view, CSJA6, depth 33.8–33.9 m, Reg. No. K3–005. (7, 8) Spiroloculina exmia: (7) side view, CSJA6, depth 47.6–47.7 m, Reg. No. K3–020; (8) apertural view, CSJA6, depth 47.6–47.7 m, Reg. No. K3–016. (9, 10) Spiroloculina jucunda: (9) side view, CSJA6, depth 34.2–34.3 m, Reg. No. K3–021; (10) apertural view, CSJA6, depth 33.8–33.9 m, Reg. No. K3–022. (11) Lagena hispida, side view, CSJA6, depth 17.2–17.3 m, Reg. No. K2–007.
1839a Quinqueloculina lamackiana Reference d’Orbignyd’Orbigny, p. 189, pl. 11, figs. 14, 15.
1884 Quinqueloculina cuvieriana; Reference BradyBrady, p. 162, pl. 5, figs. 1–3.
1929 Quinqueloculina lamarckiana; Reference CushmanCushman, p. 26, pl. 2, figs. 6a–6c.
1965 Quinqueloculina lamarckiana; Reference He, Hu and WangHe, Hu, and Wang, p. 61, pl. 2, figs. 1a–1c.
1965 Quinqueloculina lamarckiana minuscule Reference He, Hu and WangHo, Hu, and Wang; He, Hu, and Wang, p. 61, pl. 2, figs. 2a–2c.
1988 Quinqueloculina lamarckiana; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 127, pl. 13, figs. 10–12.
Occurrence
Widely distributed in the world oceans; Recent coastal water and Quaternary sediments of Bohai Sea, Yellow Sea, East China Sea, and South China Sea (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988); Pliocene in Taiwan, China (He et al., Reference He, Hu and Wang1965); Tropical Pacific (11–174 m; Jones, Reference Jones1994).
Remarks
This species was recognized by the broad elliptic shape and the sharply keeled periphery of the test. In this study, a wide variety was observed from nearly 0.1 mm (Fig. 3.1a, 3.1b) to 1 mm (Fig. 3.2, 3.3). The third chambers of the front view in the adult forms usually elevated as a keel, while juvenile forms have the convex, round ridge for this chamber. He et al. (Reference He, Hu and Wang1965) erected the smaller specimens to a new subspecies, which is considered here as a juvenile form of Quinqueloculina lamarckiana d’Orbigny (Reference d’Orbigny1839a). Cushman (Reference Cushman1929) pointed that the species has an elliptical neck with a narrow elongate tooth. He (1965) reported a bifurcate top of the tooth. The specimens observed in this study have a narrow elongate tooth with or without a much shorter neck.
Quinqueloculina venusta Karrer, Reference Karrer1868
1868 Quinqueloculina venusta Reference KarrerKarrer, p. 147, pl. 2, fig. 6.
1917 Quinqueloculina venusta; Reference CushmanCushman, p. 45, pl. 11, fig. 1.
1957 Quinqueloculina lamarckiana; Reference Todd and BronnimannTodd and Bronnimann, p. 27, pl. 3, fig.12.
1965 Quinqueloculina venusta; Reference He, Hu and WangHe, Hu, and Wang, p. 60, pl. 2, figs. 5a–5c.
1990 Quinqueloculina venusta; Reference UjiiéUjiié, p, 15, pl. 3, figs. 3a, 3b, 4a, 4b.
Occurrence
Pliocene in Japan; Miocene in Romania and Yugoslavia; Recent in Pacific and Atlantic oceans; Jiangsu and Shanghai, China (He et al., Reference He, Hu and Wang1965).
Remarks
Cushman (Reference Cushman1917) reported that this species has a short contracted neck with thickened lip and a short simple tooth. He et al. (Reference He, Hu and Wang1965) presented specimens with slightly bifurcate top of the tooth. In this study, no definite lip can be observed. Due to its elongated test and wide short tooth, the specimens of Quinqueloculina lamarckiana d’Orbigny (Reference d’Orbigny1839a) described by Todd and Bronnimann (Reference Todd and Bronnimann1957) are referred to Quinqueloculina venusta Karrer (Reference Karrer1868).
Genus Spiroloculina d’Orbigny, Reference d’Orbigny1826
Spiroloculina exmia Cushman, Reference Cushman1922a
1922a Spiroloculina exmia Reference CushmanCushman, p. 61, pl. 11, fig. 2.
1929 Spiroloculina exmia; Reference CushmanCushman, p. 42, pl. 8, figs. 7a, 7b.
1965 Spiroloculina exmia; Reference He, Hu and WangHe, Hu, and Wang, p. 72, pl. 4, figs. 5a, 5b.
Occurrence
Recent tropical Pacific; Jiangsu, China (He et al., Reference He, Hu and Wang1965).
Remarks
This species possesses rapidly increased and tapered chambers toward the apertural end. He et al. (Reference He, Hu and Wang1965) reported that the early chambers are inclined and convex. The specimens reported here have a comparatively shorter neck.
Spiroloculina laevigata Cushman and Todd, Reference Cushman and Todd1944
Figure 4 SEM photos of the foraminifers from Core CSJA6, Nantong, Jiangsu and Core LZK1, Hengsha Island, Shanghai. All scale bars are 100 μm. (1, 2) Spiroloculina laevigata: (1) side view, CSJA6, depth 47.6–47.7 m, Reg. No. K3–018; (2) apertural view, CSJA6, depth 47.6–47.7 m, Reg. No. K3–019. (3, 4) Lagena spicata: (3) side view, CSJA6, depth 20.8–20.9 m, Reg. No. K2–005; (4) side view, CSJA6, depth 13.8–13.9 m, Reg. No. K2–003. (5) Lagena substriata: side view, LZK1, depth 9.5–9.6 m, Reg. No. K2–008. (6, 7) Fissurina laevigata: (6) side view, LZK1, depth 12.3–12.4 m, Reg. No. K1–080; (7) apertural view, CSJA6, depth 23.2–23.3 m, Reg. No. K1–079. (8a, 8b) Fissurina orbignyana: (8a) side view, CSJA6, depth 7.5–7.6 m, Reg. No. K1–083; (8b) apertural view, CSJA6, depth 23.2–23.3 m, Reg. No. K1–083. (9a, 9b) Globulina minuta: (9a) side view, LZK1, depth 12.3–12.4 m, Reg. No. K1–087; (9b) apertural view, LZK1, depth 12.3–12.4 m, Reg. No. K1–087. (10) Bulmina marginata, side view, CSJA6, depth 31.2–31.3 m, Reg. No. K4–010.
1944 Spiroloculina laevigata Reference Cushman and ToddCushman and Todd, p. 67, pl. 9, figs. 26–29.
1965 Spiroloculina laevigata; Reference He, Hu and WangHe, Hu, and Wang, p. 72, pl. 4, figs. 7a, 7b.
1988 Spiroloculina laevigata; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 126, pl. 12, fig. 17.
Holotype
(USNM CC 41730 ) in National Museum of Natural History, Smithsonian Institution, Washington, D.C.
Occurrence
Recent Pacific; Jiangsu, China (He et al., Reference He, Hu and Wang1965).
Remarks
This species is close to Spiroloculina exmia Cushman (Reference Cushman1922a). Compared with the latter, the test of this species is more symmetric, and the chambers keep the same width from the base to the apertural end. The specimens illustrated here are more elongate than the holotype.
Suborder Lagenina Lankester, Reference Lankester1885
Family Nodosariidae Ehrenberg, Reference Ehrenberg1838
Genus Lagena Walker and Jacob, Reference Walker and Jacob1798
Lagena hispida Reuss, Reference Reuss1858
1858 Lagena hispida Reference ReussReuss, p. 434.
1884 Lagena hispida; Reference BradyBrady, p. 450, pl. 57, figs. 1–4.
1965 Lagena hispida; Reference He, Hu and WangHe, Hu, and Wang, p. 77, pl. 5, fig. 12.
1988 Lagena hispida; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 135, pl. 16, fig. 12.
1990 Lagena hispida; Reference UjiiéUjiié, p, 18, pl. 5, fig. 2.
Occurrence
Oligocene in Germany; Quaternary in Denmark; Pliocene in U.S.A. and Japan; Recent in Pacific and Atlantic oceans; Yellow Sea and shelf of East China Sea (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988).
Remarks
The wall of this species is ornamented with fine spines. According to Brady (Reference Brady1884), the test varies from flask-shaped to subglobular, and in some specimens, the basal end is drawn out into a stout spine, which was also reported by Ujiié (Reference Ujiié1990). The stout spine out of the base was described, but not observed in the plates illustrated by He et al. (Reference He, Hu and Wang1965). The specimens here and reported by Wang et al. (Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988) showed no spine for the subglobular test.
Lagena spicata Cushman and McCulloch, Reference Cushman and McCulloch1950
1950 Lagena sulcata var. spicata Reference Cushman and McCullochCushman and McCulloch, p. 360, pl. 48, figs. 3–7.
1965 Lagena striata; Reference He, Hu and WangHe, Hu, and Wang, p. 76, pl. 5, fig. 11.
1988 Lagena spicata; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 135, pl. 16, figs. 9, 10.
Occurrence
Widely distributed in world oceans; seldom found in shelf sediments of East China Sea (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988).
Remarks
There is a considerable amount of variation in this species. Cushman and McCulloch (Reference Cushman and McCulloch1950) erected this species from Lagena sulcata in having the basal end drawn out into a stout spine while the latter has coarse longitudinal costae, extending to the base and forming numerous spines. The specimens reported here and by Wang et al (Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988) have stronger stout spines than those from He et al. (Reference He, Hu and Wang1965). Circular costae can be observed on the neck of specimens in this study and in those of Wang et al (Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988). The specimens in this study vary from flask-shaped to pyriform.
Lagena substriata Williamson, Reference Williamson1858
1858 Lagena vulgaris var. substriata Reference WilliamsonWilliamson, p. 7, pl. 1, fig. 14.
1913 Lagena striata var. substriata; Reference CushmanCushman, p. 20, pl. 8, figs. 1–3.
1923 Lagena substriata; Reference CushmanCushman, p. 56, pl. 10, fig.11.
1965 Lagena substriata; Reference He, Hu and WangHe, Hu, and Wang, p. 77, pl. 5, figs. 7, 8.
1988 Lagena substriata; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 134, pl. 16, fig. 17.
1990 Lagena substriata; Reference UjiiéUjiié, p. 19, pl. 5, fig. 7.
Occurrence
Widely distributed in coastal water of the world oceans; inner and middle shelf of East China Sea (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988).
Remarks
This species is characterized by the costulate surface extending up on to the neck, often to its end, and usually spirally arranged on the neck (Cushman, Reference Cushman1913). He (1965) and Ujiié (Reference Ujiié1990) reported specimens similar to those illustrated here. The test is elongate compared with Lagena spicata Cushman and McCulloch (Reference Cushman and McCulloch1950).
Family Polymorphinidae d’Orbigny, Reference d’Orbigny1839a
Genus Fissurina Reuss, Reference Reuss1850
Fissurina laevigata Reuss, Reference Reuss1850
1850 Fissurina laevigata Reference ReussReuss, p. 366, pl. 46, fig. 1.
1965 Fissurina laevigata; Reference He, Hu and WangHe, Hu, and Wang, p. 79, pl. 5, fig. 14.
1988 Fissurina laevigata; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 144, pl. 19, fig. 13.
1990 Fissurina sp.; Reference UjiiéUjiié, p. 23, pl. 7, fig. 13.
1990 Fissurina periperforata; Reference UjiiéUjiié, p. 25, pl. 8, fig. 10.
Occurrence
Widely distributed in coastal water of the world oceans; shelf of East China Sea (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988); 4–5715 m (Jones, Reference Jones1994).
Remarks
The species has a compressed chamber with single-keel periphery. The Fissurina laevigata specimen illustrated by Ujiié (Reference Ujiié1990) is different from the present species by lacking the distinct peripheral keel and having a smaller aperture. Fissurina sp. and Fissurina periperforata Ujiié (Reference Ujiié1990) are similar to the present species, although Fissurina periperforata Ujiié (Reference Ujiié1990) has a more elongate form.
Fissurina orbignyana Seguenza, Reference Seguenza1862
1862 Fissurina orbignyana Reference SeguenzaSeguenza, p. 66, pl. 2, figs. 25, 26.
1971 Fissurina orbignyana; Reference MurrayMurray, p. 99, pl., 40, figs. 1–5.
1988 Fissurina orbignyana; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 144, pl. 19, figs. 6, 7.
Occurrence
Widely distributed in coastal water of the world oceans; Recent Pacific, Atlantic, and Gulf of Mexico; shelf of East China Sea (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988).
Remarks
This species is distinguished by its three-keel periphery and the most-prominent central one.
Genus Globulina d’Orbigny, Reference d’Orbigny1839a
Globulina minuta (Roemer, Reference Roemer1838)
1838 Polymorphina minuta Reference RoemerRoemer, p. 386, pl. 3, fig. 35.
1863 Polymorphina sororia Reference ReussReuss, p. 71, fig. 16.
1930 Globulina minuta; Reference Cushman and OzawaCushman and Ozawa, p. 83, pl. 20, figs. 3, 4.
1965 Globulina minuta; Reference He, Hu and WangHe, Hu, and Wang, p. 81, pl. 5, fig. 19.
Occurrence
Early Pleistocene in Italy; inner shelf of East China Sea (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988).
Remarks
This species is distinguished by the fusiform test and fewer chambers. The last chamber is much bigger than others. Polymorhina sororia Reuss (Reference Reuss1863) was considered a junior synonym of Globulina minuta (Roemer, Reference Roemer1838) by Cushman and Ozawa (Reference Cushman and Ozawa1930). The specimen reported here is comparatively acute for both the basal and apertural ends, with a tiny acicular spine developed in the basal end.
Suborder Rotaliina Delage and Hérouard, Reference Delage and Hérouard1896
Superfamily Buliminacea Jones in Griffith and Henfrey, Reference Griffith and Henfrey1875
Family Buliminidae Jones in Griffith and Henfrey, Reference Griffith and Henfrey1875
Genus Bulimina d’Orbigny, Reference d’Orbigny1826
Bulimina marginata d’Orbigny, Reference d’Orbigny1826
1826 Bulimina marginata Reference d’Orbignyd’Orbigny, p. 269, pl. 12, figs. 10–12.
1922b Bulimina marginata; Reference CushmanCushman, p. 91, pl. 21, figs. 4, 5.
1965 Bulimina marginata; Reference He, Hu and WangHe, Hu, and Wang, p. 84, pl. 6, fig. 7.
1965 Bulimina marginospinata ovata; Reference He, Hu and WangHe, Hu, and Wang, p. 85 pl. 6, fig. 8.
1988 Bulimina marginata; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 144, pl. 21, fig. 6, pl. 34, figs. 11–15.
Occurrence
Widely distributed in coastal water of the world oceans; inner and middle shelf of East China Sea (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988).
Remarks
This species has a great number of varieties for the juvenile and adult forms. Wang et al. (Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988) conducted a morphometric analysis of 200 tests from the surface sediments of the East China Sea, and displayed a concentrated and continuous distribution for tests of different length and breadth, which suggests that these short oval or/and high fusiform forms belong to the same species. The specimen illustrated here has a shorter test, resembling the juvenile form of Bulimina marginata d’Orbigny (Reference d’Orbigny1826). The rim of the early chambers has a series of short blunt spines, while the later chamber has a series of crenulations.
Family Bolivinitidae Cushman, Reference Cushman1927
Genus Bolivina d’Orbigny, Reference d’Orbigny1839b
Bolivina robusta Brady, Reference Brady1881
Figure 5 SEM photos of the foraminifers from Core CSJA6, Nantong, Jiangsu and Core LZK1, Hengsha Island, Shanghai. All scale bars are 100 μm. (1, 2) Bolivina robusta: (1) side view, CSJA6, depth 13.2–13.3 m, Reg. No. K1–023; (2) edge view. CSJA6, depth 13.2–13.3 m, Reg. No. K1–025. (3, 4) Brizalina striatula: (3) side view, LZK1, depth 12.7–12.8 m, Reg. No. K1–034; (4) edge view, LZK1, depth 12.3–12.4 m, Reg. No. K4–009. (5, 6) Epistominella naraensis: (5) ventral view, right-coiled, LZK1, depth 12.7–12.8 m, Reg. No. K1–067; (6) edge view, left-coiled, LZK1, depth 12.7–12.8 m, Reg. No. K1–069. (7–9) Rosalina bradyi: (7) ventral view, LZK1, depth 30.7–30.8 m, Reg. No. K3–012; (8) edge view, CSJA6, depth 30.8–30.9 m, Reg. No. K4–038; (9) dorsal view, CSJA6, depth 34.2–34.3 m, Reg. No. K3–013. (10–12) Buccella frigida: (10) ventral view, CSJA6, depth 20.8–20.9 m, Reg. No. K1–036; (11) ventral view, CSJA6, depth 36.2–36.3 m, Reg. No. K4–008; (12) dorsal view, CSJA6, depth 25.5–25.6 m, Reg. No. K1–033.
1881 Bolivina robusta Reference BradyBrady, p. 57.
1922b Bolivina robusta var.; Reference CushmanCushman, p. 46, pl. 6, fig. 6.
1965 Bolivina robusta; Reference He, Hu and WangHe, Hu, and Wang, p. 87, pl. 6, fig. 13.
1965 Bolivina cochei; Reference He, Hu and WangHe, Hu, and Wang, p. 88, pl. 6, figs. 16, 17.
1965 Bolivina obscura; Reference He, Hu and WangHe, Hu, and Wang, p. 88, pl. 7, figs. 1–3.
1988 Bolivina robusta; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 147, pl. 34, figs. 1–5.
1994 Bolivina robusta; Reference JonesJones, pl. 53, figs. 7–9.
Holotype
Syntype (BMNH ZF1194) from Challenger Sta. 191A , Kai Island, Central Pacific (1061 m); (BMNH ZF1195) from Challenger Sta. 174B, Fiji, Pacific (2041 m).
Occurrence
Recent coastal water and Quaternary sediments of Bohai Sea, Yellow Sea, East China Sea and South China Sea (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988); 13–3475 m (Jones, Reference Jones1994).
Remarks
This species has great variability in morphology. Wang et al (Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988) reported the megalospheric and microspheric tests. The specimens illustrated here are elongated cuneiform with blunt basal end, resembling a microspheric test. It was also reported that a long sharp spine may exist for this species (Jones, Reference Jones1994, p. 58, pl. 53, figs. 8, 9).
Superfamily Discorbacea Ehrenberg, Reference Ehrenberg1838
Family Discorbidae Ehrenberg, Reference Ehrenberg1838
Genus Rosalina d’Orbigny, Reference d’Orbigny1826
Rosalina bradyi (Cushman, Reference Cushman1915)
1915 Discobis globularis var. bradyi Reference CushmanCushman, p. 12, pl. 8, fig. 1.
1931 Discorbis globularis; Reference CushmanCushman, p. 22, pl. 4, figs. 9a–9c.
1960 Rosalina bradyi; Reference BarkerBarker, pl. 86, fig. 8.
1965 Rosalina bradyi; Reference He, Hu and WangHe, Hu, and Wang, p. 89, pl. 8, figs. 5a–5c, 6a–6c.
1988 Rosalina bradyi; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 156, pl. 23, fig. 12.
Holotype
USNM 9027 from Alabatross station D4863 in 194 m off Japan (Cushman, Reference Cushman1915, pl. 8, fig. 1).
Occurrence
Neogene to Recent in Japan; Recent Pacific; East China Sea, South China Sea; inner shelf in East China Sea (He et al., Reference He, Hu and Wang1965; Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988).
Remarks
The test of this species is compressed. The specimens illustrated here clearly show the wall difference between the coarse-perforated dorsal and fine-perforated ventral sides (Figure 5.8). The umbilical lobe of specimens is scattered and thickened.
Genus Buccella Andersen, Reference Andersen1952
Buccella frigida (Cushman, Reference Cushman1922c)
1922c Pulvinulina frigida Reference CushmanCushman, p. 144.
1931 Eponides frigida; Reference CushmanCushman, p. 45.
1952 Bucella frigida; Reference AndersenAnderson, p. 144, figs. 4–6.
1965 Buccella frigida; Reference He, Hu and WangHe, Hu, and Wang, p. 93, pl. 8, figs. 4a–4c.
1988 Buccella frigida; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 157, pl. 23, figs. 3, 4.
Holotype
Lectotype (USNM CC 3032) from station 5, bay between Black Whale and Olasks Harbors, east coast of Hudson Bay at 18 m water depth (Cushman, Reference Cushman1931).
Occurrence
Recent Arctic, Okhotsk Sea, Japan Sea, Bering Sea, Pacific, northern Atlantic; Bohai Sea, Yellow Sea, northwest of East China Sea, and the South China Sea; Quaternary in Jiangsu Province (He et al.,Reference He, Hu and Wang1965, Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988); 34–402 m (Jones, Reference Jones1994).
Remarks
The dorsal side of this species is filled with an amorphous material radiating out from the umbilical region. These materials usually distribute along the sutures. Less amorphous material may be observed for the later sutures. Supplementary apertures lie at the ends of the sutures, forming bigger pores and usually covered by the same amorphous material (Fig. 5.11). The amorphous material may be more around the supplementary aperture than the central umbilicus area. A slightly keeled periphery was also observed (NHM ZF 2220–2221). However, the keel is indistinct in the specimens of this study.
Genus Helenina Saunders, Reference Saunders1961
Helenina anderseni (Warren, Reference Warren1957)
Figure 6 SEM photos of the foraminifers from Core CSJA6, Nantong, Jiangsu and Core LZK1, Hengsha Island, Shanghai. All scale bars are 100 μm. (1–3) Cancris auriculus: (1) ventral view, CSJA6, depth 34.8–34.9 m, Reg. No. K1–044; (2) edge view, CSJA6, depth 34.8–34.9 m, Reg. No. K1–046; (3) dorsal view, CSJA6, depth 34.8–34.9 m, Reg. No. K1–045. (4–6) Helenina anderseni: (4) ventral view, CSJA6, depth 46.5–46.6 m, Reg. No. K1–029; (5) edge view, CSJA6, depth 46.5–46.6 m, Reg. No. K4–009; (6) dorsal view, CSJA6, depth 46.5–46.6 m, Reg. No. K1–030. (7, 8) Hyalinea balthica: (7) side view, CSJA6, depth 35.2–35.3 m, Reg. No. K4–023; (8) edge view, CSJA6, depth 34.8–34.9 m, Reg. No. K4–024; (9–11) Cibicides lobatulus: (9) ventral view, CSJA6, depth 11.8–11.9 m, Reg. No. K1–047; (10) edge view, CSJA6, depth 17.2–17.3 m, Reg. No. K1–049; (11) dorsal view, CSJA6, depth 7.5–7.6 m, Reg. No. K1–048.
1957 Pseudoeponides anderseni Reference WarrenWarren, p. 39, pl. 4, figs. 12–15.
1957 Helenina anderseni; Reference SaundersSaunders, p. 374.
1961 Helenina anderseni; Reference SaundersSaunders, p. 148.
1988 Helenina anderseni; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 158, pl. 24, figs. 1, 2.
2011 Helenina anderseni; Reference Gennari, Rosenberg, Spezzaferri, Berger, Fleitmann, Preusser, Al-Shanti and MatterGennari et al., p. 249, pl. 1, figs. 1–6, pl. 2, figs. 1–4.
Holotype
(LSUGM 2009) from wet marsh on the northeast side of Crosscut Canal at Bay Pomme d’Or (Warren, Reference Warren1957, pl. 4, fig. 12–15).
Occurrence
Widely distributed in low-salinity coastal water; inner shelf of East China Sea (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988).
Remarks
Warren (Reference Warren1957) erected this species, which usually has supplementary apertures within the deeply incised sutures dorsally near the junction of spiral and septal sutures, and within the incised sutures ventrally near their middle points. Gennari et al. (Reference Gennari, Rosenberg, Spezzaferri, Berger, Fleitmann, Preusser, Al-Shanti and Matter2011) reported a large number of morphological varieties, especially for different shapes of the sutures. The specimens here are more inflated. The supplementary apertures of specimens can be observed on the middle part of the septal sutures instead of near the junction, and are much narrower, showing a deeply incised slit. The supplementary apertures reported by Gennari (2011) are wider near umbilical region, and even triangular.
Family Cibicididae Cushman, Reference Cushman1927
Genus Cibicides de Montfort, Reference de Montfort1808
Cibicides lobatulus (Walker and Jacob, Reference Walker and Jacob1798)
1798 Nautilus lobatulus Reference Walker and JacobWalker and Jacob, p. 642, pl. 14, fig. 36.
1884 Truncatulina lobatulus (Walker and Jacob); Reference BradyBrady, pl. 92, fig.10, pl. 93, figs. 1, 4, 5.
1931 Cibicides lobatula; Reference CushmanCushman, p. 118, pl. 21, figs. 3a–3c.
1978 Cibicides lobatulus; Reference Cheng and ZhengCheng and Zheng, p. 232, pl. 21, figs. 2a–2c.
1988 Cibicides lobatulus; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 162, pl. 25, figs. 12–14.
Holotype
(BMNH ZF2532) from Challenger Station 172, Friendly Islands, Pacific (33 m ) (Brady, Reference Brady1884, pl. 92, fig. 10).
Occurrence
Widely distributed in coastal water of the world oceans; middle and outer shelf of East China Sea and South China Sea (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988).
Remarks
Large variations in morphology are assigned to this species. Specimens with keeled periphery or depressed umbilicus were reported by Brady (Reference Brady1884). The specimens here are more inflated with a round periphery, while those of Cushman (Reference Cushman1931) and Wang (1988) have compressed chambers with obviously lobulated periphery.
Superfamily Rotaliacea Ehrenberg, Reference Ehrenberg1839
Family Rotaliidae Ehrenberg, Reference Ehrenberg1839
Genus Ammonia Brünnich Reference Brünnich1772
Ammonia pauciloculata (Phleger and Parker, Reference Phleger and Parker1951)
Figure 7 SEM photos of the foraminifers from Core CSJA6, Nantong, Jiangsu and Core LZK1, Hengsha Island, Shanghai. All scale bars are 100 μm. (1–3) Ammonia pauciloculata: (1) ventral view, CSJA6, depth 31.2–31.3 m, Reg. No. K4–003; (2) edge view, LZK1, depth 27.7–27.8 m, Reg. No. K4–005; (3) dorsal view, CSJA6, depth 31.2–31.3 m, Reg. No. K4–004. (4–6) Ammonia compressiuscula: (4) ventral view, CSJA6, depth 34.2–34.3 m, Reg. No. K1–018; (5) edge view, CSJA6, depth 34.2–34.3 m, Reg. No. K1–019; (6) dorsal view, CSJA6, depth 21.5–21.6 m, Reg. No. K1–017. (7–9) Ammonia ketienziensis: (7) ventral view, CSJA6, depth 33.8–33.9 m, Reg. No. K4–035; (8) edge view, CSJA6, depth 34.2–34.3 m, Reg. No. K4–034; (9) dorsal view, CSJA6, depth 34.2–34.3 m, Reg. No. K4–033. (10–12) Ammonia beccarii: (10) ventral view, CSJA6, depth 7.5–7.6 m, Reg. No. K1–007; (11) edge view, CSJA6, depth 7.5–7.6 m, Reg. No. K1–009; (12) dorsal view, CSJA6, depth 7.5–7.6 m, Reg. No. K1–008.
1951 “Rotalia” pauciloculata Reference Phleger and ParkerPhleger and Parker, p. 23, pl, 12, figs. 8, 9.
1965 Ammonia nantongensis Reference He, Hu and WangHo, Hu, and Wang; He, Hu, and Wang, p. 104, pl. 11, figs. 5a–5c.
1988 Ammonia pauciloculata; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 166, pl. 27, figs. 8–10.
Holotype
(Sample 1) from Core 498 (Phleger and Parker, Reference Phleger and Parker1951, pl. 12, figs. 8, 9).
Occurrence
Gulf of Mexico; coastal water in China seas, inner shelf of East China Sea; Quaternary coastal sediments in China; 0–50m (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988).
Remarks
Supplementary apertures that are perpendicular to the middle of the septal sutures on the ventral side, as noted by Wang et al. (Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988), can be observed in the holotype illustrated by Phleger and Parker (Reference Phleger and Parker1951). The specimens in this study and Ammonia nantongensis Ho, Hu, and Wang (Reference He, Hu and Wang1965) also show this morphological character, while the subspecies Ammonia pauciloculata major described by He et al. (Reference He, Hu and Wang1965) cannot be assigned to this species because it has a large number of chambers for the last whorl and straight sutures.
Genus Cavarotalia Müller-Merz, Reference Müller-Merz1980
Cavarotalia annectens (Parker and Jones, Reference Parker and Jones1865)
Figure 8 SEM photos of the foraminifers from Core CSJA6, Nantong, Jiangsu and Core LZK1, Hengsha Island, Shanghai. All scale bars are 100 μm. (1–3) Cavarotalia annectens: (1) ventral view, LZK1, depth 21.7–21.8 m, Reg. No. K1–004; (2) edge view, LZK1, depth 21.7–21.8 m, Reg. No. K4–001; (3) dorsal view, LZK1, depth 21.7–21.8 m, Reg. No. K1–005. (4, 5) Cribrononion subincertum: (4) side view, CSJA6, depth 23.2–23.3 m, K4–012; (5) edge view, CSJA6, depth 23.2–23.3 m, Reg. No. K4–013. (6, 7) Cribrononion vitreum: (6) side view, CSJA6, depth 23.2–23.3 m, Reg. No. K4–014; (7) edge view, LZK1, depth 12.3–12.4 m, Reg. No. K4–015. (8–10) Elphidiella kiangsuensis: (8) side view, CSJA6, depth 23.2–23.3 m, Reg. No. K4–026; (9) edge view, CSJA6, depth 5.5–5.6 m, Reg. No. K1–055. (10) side view (Guo et al., Reference Guo, Li, Wang, Lan and Ding2014). (11, 12) Elphidium advenum: (11) side view, CSJA6, depth 47.6–47.7 m, Reg. No. K1–056; (12) edge view, CSJA6, depth 47.6–47.7 m, Reg. No. K1–057.
1865 Rotalia beccarii var. annectens Reference Parker and JonesParker and Jones, p. 387, pl. 19, figs. 11a–11c.
1940 Streblus annectens; Reference IshizakiIshizaki, p. 49, pl. 3, figs. 12a, 12b, 13a, 13b.
1965 Ammonia annectens; Reference He, Hu and WangHe, Hu, and Wang, p. 103, pl. 11, figs. 3a–3c.
1980 Cavarotalia annectens; Reference Müller-MerzMüller-Merz, p. 37, figs. 26, 27.
1988 Cavarotalia annectens; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 168, pl. 27, figs. 12, 13.
Occurrence
Miocene in India; shallow water in Pacific and Indian oceans; shelf of China seas; Quaternary in Taiwan, China; Quaternary coastal sediments in East China; 0–50 m, East China Sea (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988).
Remarks
Deeply incised, fishbone-like sutures taper from the middle to the periphery in ventral side. The large transparent umbilical plug also distinguishes it from Ammonia.
Family Elphidiidae Galloway, Reference Galloway1933
Genus Cribrononion Thalmann, Reference Thalmann1947
Cribrononion subincertum (Asano, Reference Asano1950)
1950 Elphidium subincertum Reference AsanoAsano, p. 10, figs. 56, 57.
1965 Cribrononion gnythosuturatum; Reference He, Hu and WangHe et al., p. 115, pl. 14, figs. 5a, 5b.
1965 Cribrononion sp.; Reference He, Hu and WangHe et al., p. 115, pl. 14, figs. 3a, 3b.
1978 Cribrononion incertum; Reference Zheng, Cheng, Wang and FuZheng et al., p. 58, pl. 8, figs. 15, 16.
1980a Cribrononion subincertum; Reference Wang, Min and BianWang et al., pl. 9, figs. 22, 23.
1988 Cribrononion subincertum; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 168, pl. 28, figs. 1–4.
Occurrence
Shallow water in high-latitude North Pacific and North Atlantic; Recent and Quaternary coastal sediments in Bohai Sea, Yellow Sea, and East China Sea; 0–50m in East China Sea; 10–30% salinity, coastal water off Jiangsu and Zhejiang, China (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988).
Remarks
The specimens in this study possess the long slit sutures. Test slightly compressed, as show in Figure 8.4, or inflated (Fig. 8.5). Wang et al. (Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988) pointed out that the juvenile forms are often more inflated than the adult. It was reported that the aperture is made up of a row of pores (He et al., Reference He, Hu and Wang1965). Due to the granular cover on the base of the apertural face, the pores cannot be observed in the specimens illustrated here.
Cribrononion vitreum Wang and Gu, Reference Wang and Gu1980
1980 Cribrononion vitreum;Reference WangWang and Gu, pl. 16, fig. 13.
1988 Cribrononion vitreum; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 169, pl. 27, figs. 14, 15.
2012 Cribrononion vitreum; Reference Li, Wang, Kong, Lin, Li and ZhangLi et al., pl. 2, figs. 11, 12.
Holotype
(TJU H1560) from Core Lp25, depth 24–35.91 m, east coast of Liaohe estuary, Panshan, Liaoning Province (Wang and Gu, Reference Wang and Gu1980, pl. 16, fig. 13).
Occurrence
Recent and Quaternary coastal sediments of Bohai Sea, East China Sea, and Yellow Sea; inner shelf and estuary in East China Sea, 10–30% salinity (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988).
Remarks
Wang et al. (Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988) pointed out that there are several pores on the middle of the aperture face, which also has been observed by Li et al. (Reference Li, Wang, Kong, Lin, Li and Zhang2012). The specimens illustrated here have lost the last chamber. But the aperture, a row of slits, is the same as those described by Wang et al. (Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988). The pores on the aperture face in this study cannot be observed.
Genus Elphidiella Cushman, Reference Cushman1936a
Elphidiella kiangsuensis (Ho, Hu, and Wang, Reference He, Hu and Wang1965)
1965 Cribrononion kiangsuensis Ho, Hu, and Wang; Reference He, Hu and WangHe, Hu, and Wang, p. 114, pl. 13, fig. 13.
1978 Elphidiella kiangsuensis; Reference Zheng, Cheng, Wang and FuZheng et al., p. 60, pl. 9, figs. 1, 13.
1988 Elphidiella kiangsuensis; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 171, pl. 29, figs. 12, 13.
2014 Elphidiella kiangsuensis; Reference Guo, Li, Wang, Lan and DingGuo et al., pl. 1, figs. 5, 6.
Holotype
(NIGP 14685) from Binhai, Jiangsu, China (He et al., pl. 13, fig. 13).
Description
Test planspiral, entirely involute, oval in side view, bilaterally symmetrical, sides nearly parallel in edge view; periphery rounded; chambers 8–10 in the last whorl, increasing gradually, gently inflated; umbilicus flattened; sutures curved, nearly flush with the surface, often consisting of two rows of small round pores; wall smooth, translucent, finely perforate; oval apertural face; aperture comb-like on the base of the face.
Occurrence
Quaternary and Recent coastal sediments in Bohai Sea, Yellow Sea and East China Sea (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988).
Remarks
The pores in the sutures of specimens in this study are less distinct, the same as shown by He et al. (Reference He, Hu and Wang1965). The suture pores are more clear in the specimens (Fig. 8.10) reported by Guo et al. (Reference Guo, Li, Wang, Lan and Ding2014), in which two rows of pores form a wide suture zone. Depressed slit-like sutures also were reported in the East China Sea (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988).
Genus Elphidium de Montfort, Reference de Montfort1808
Elphidium hispidulum Cushman, Reference Cushman1936b
Figure 9 SEM photos of the foraminifers from Core CSJA6, Nantong, Jiangsu and Core LZK1, Hengsha Island, Shanghai. All scale bars are 100 μm. (1, 2) Elphidium hispidulum: (1) side view, CSJA6, depth 46.5–46.6 m, Reg. No. K1–060; (2) edge view, CSJA6, depth 25.5–25.6 m, Reg. No. K4–029. (3) Elphidium limpidum: side view, CSJA6, depth 46.5–46.6 m, Reg. No. K1–062. (4, 5) Elphidium magellanicum: (4) side view, CSJA6, depth 2.2–2.3 m, Reg. No. K1–065; (5) edge view, CSJA6, depth 20.8–20.9 m, Reg. No. K1–066. (6, 7) Protelphidium tuberculatum: (6) side view, CSJA6, depth 13.5–13.6 m, Reg. No. K2–022; (7) edge view, CSJA6, depth 25.5–25.6 m, Reg. No. K2–023. (8, 9) Pseudononionella variabilis: (8) ventral view, CSJA6, depth 7.5–7.6 m Reg. No. K2–024; (9) dorsal view, CSJA6, depth 36.8–36.9 m, Reg. No. K2–025. (10–12) Florilus scaphus: (10) ventral view, LZK1, depth 12.3–12.4 m, Reg. No. K1–076; (11) edge view, LZK1, depth 12.3–12.4 m, Reg. No. K1–078; (12) dorsal view, LZK1, depth 12.7–12.8 m, Reg. No. K4–022.
1936b Elphidium hispidulum Reference CushmanCushman, p. 83, pl. 14, figs. 13a, 13b.
1978 Elphidium hispidulum; Reference Zheng, Cheng, Wang and FuZheng et al., p. 55, pl. 7, fig. 9.
1988 Elphidium hispidulum; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 170, pl. 29, figs. 16, 17.
Holotype
(USNM CC 23028) from 7–26 m, Albany Passage, Australia (Cushman, Reference Cushman1936b, pl. 14, figs. 13a, 13b).
Occurrence
Southern Australia and Gulf of Paria; surface sediments in Bohai Sea, Yellow Sea and East China Sea.
Remarks
The bosses in the umbilicus are partially separated for specimens in this study. A row of low papillae in the early portion of the sutures is more distinct than those of Wang et al. (Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988) and He et al. (Reference He, Hu and Wang1965).
Elphidium magellanicum Heron-Allen and Earland, Reference Heron-Allen and Earland1932
1932 Elphidium (Polystomella) magellanicum Reference Heron-Allen and EarlandHeron-Allen and Earland, p. 440, pl. 16, figs. 26–28.
1978 Elphidium magellanicum; Reference Zheng, Cheng, Wang and FuZheng et al., p. 56, pl. 8, fig. 3.
1978 Elphidiononion magellanicum; Reference Banner and CulverBanner and Culver, pl. 9, fig. 16.
1980b Elphidium magellanicum; Reference Wang, Min and GaoWang et al., p. 98, pl. 11, fig. 16.
1988 “Elphidium magellanicum”; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 169, pl. 28, figs. 5, 11–13.
Holotype
(BMNH HA508-90) from WS 89, depth 23 m, eastern entrance to the Straits of Magellan (Heron-Allen and Earland, pl. 16, figs. 26–28).
Occurrence
Coastal water and Quaternary coastal sediments in Bohai Sea, Yellow Sea, and East China Sea (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988).
Remarks
Wang et al. (Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988) pointed out that the specimens in the East China Sea are different from those of the Atlantic samples by a much inflated test. The specimens in this study have a less lobulate peripheral edge, close to that reported by Wang et al. (Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988). The umbilicus and the base of the apetural face are filled with fine granular matter in this study, but the granular region is much narrower and smaller than those described by Heron-Allen and Earland (Reference Heron-Allen and Earland1932).
Genus Protelphidium Haynes, Reference Haynes1956
Protelphidium tuberculatum (d’Orbigny, Reference d’Orbigny1846)
1846 Nonion tuberculatum Reference d’Orbignyd’Orbigny, p. 108, pl. 5, figs. 13, 14.
1939 Nonion tuberculatum; Reference CushmanCushman, p. 13, pl. 3, figs. 12, 16, 17.
1980a Protelphidium tuberculatum; Wang and Gu, p. 60, pl. 16, fig. 7.
1988 Protelphidium tuberculatum; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 171, pl. 29, figs. 14, 15.
Occurrence
Coastal water and Quaternary coastal sediments in Bohai Sea, Yellow Sea, and East China Sea; Yellow Sea coastal cold water; inner shelf and Late Pleistocene outer shelf sediments in East China Sea (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988).
Remarks
This species differs from Elphidium magellanicum by a small elevated umbilicus filled with a few tuberculations, and evident slit sutures. It was reported that the early whorls in this species usually appears yellow in China seas (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988).
Superfamily Cassidulinacea d’Orbigny, Reference d’Orbigny1839a
Family Caucasinidae Bykova, Reference Bykova1959
Genus Fursenkoina Loeblich and Tappen, Reference Loeblich and Tappen1961
Fursenkoina pauciloculata (Brady, Reference Brady1884)
Figure 10 SEM photos of the foraminifers from Core CSJA6, Nantong, Jiangsu and Core LZK1, Hengsha Island, Shanghai. All scale bars are 100 μm. (1, 2) Fursenkoina pauciloculata: (1) side view, CSJA6, depth 34.8–34.9 m, Reg. No. K1–086; (2) apertural view, LZK1, depth 25.5–25.6 m, Reg. No. K3–023. (3, 4) Nonion akitense: (3) side view, CSJA6, depth 23.2–23.3 m, K2–011; (4) edge view, CSJA6, depth 23.2–23.3 m, Reg. No. K2–012. (5–7) Nonionella jacksonensis: (5) ventral view, LZK1, depth 12.3–12.4 m, Reg. No. K2–015; (6) edge view, LZK1, depth 12.3–12.4 m, Reg. No. K2–013; (7) dorsal view, LZK1, depth 12.7–12.8 m, Reg. No. K2–014. (8, 9) Pullenia quinqueloba: (8) side view, ZKA4, depth 41.1–41.2 m, Reg. No. K2–027; (9) edge view, LZK1, depth 4.5–4.6 m, Reg. No. K2–028. (10, 11) Gyroidina nippoinca: (10) ventral view, LZK1, depth 19.8–19.9 m, Reg. No. K1–089; (11a) edge view, LZK1, depth 5.1–5.2 m, Reg. No. K1–090; (11b) dorsal view, LZK1, depth 5.1–5.2 m, Reg. No. K1–090.
1884 Virgulina pauciloculata Reference BradyBrady, p. 414, pl. 52, figs. 4, 5.
1965 Fursenkoina pauciloculata; Reference He, Hu and WangHe, Hu, and Wang, p. 84, pl. 6, fig. 7.
1994 Virgulina pauciloculata Brady; Reference JonesJones, pl. 52, figs. 4, 5.
Occurrence
Recent South Pacific; Jiangsu, China (He et al., Reference He, Hu and Wang1965).
Remarks
The shorter and wider specimens (Fig. 10.1) reported here are the same as those described by He et al. (Reference He, Hu and Wang1965); the elongate specimen (Fig. 10.2) is referred to those specimens described by Brady (Reference Brady1884), but lacks the short spine in the earliest chamber.
Superfamily Nonionacea Schultze, Reference Schultze1854
Family Nonionidae Schultze, Reference Schultze1854
Genus Nonionella Cushman, Reference Cushman1926
Nonionella jacksonensis Cushman, Reference Cushman1933
1933 Nonionella jacksonensis Reference CushmanCushman, p. 10, pl. 1, figs. 23a–23c.
1965 Nonionella jacksonensis; Reference He, Hu and WangHe, Hu, and Wang, p. 119, pl. 14, figs. 11a, 11b.
1988 Nonionella jacksonensis; Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and ChenWang et al., p. 176, pl. 32, figs. 1, 2.
Holotype
(USNM MO 371678) from Cooper marl, 1.6 km (1 mile) south of Moncks Corner, Berkeley Co., S.C. (Cushman, Reference Cushman1933, pl. 1, figs. 23a–23c).
Occurrence
Upper Eocene in U.S.A.; surface shelf and Quaternary coastal sediments in Yellow Sea and East China Sea; common in inner shelf and estuary of East China Sea (Wang et al., Reference Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng and Chen1988).
Remarks
It was reported that there is a slit-like aperture on the base of last chamber (He et al., Reference He, Hu and Wang1965). The aperture of specimens presented here cannot be observed due to the granular cover on the base of the apertural face. The latter chambers in this study increase slowly, comparatively.
Results
Foraminiferal specimens were only found from the depth intervals of 3–42.07 m, 1.8–65.7 m, and 0.6–46.1 m in cores ZKA4, CSJA6 and LZK1, respectively (Fig. 2). The foraminiferal abundance in Core ZKA4 is generally lower than those of the other two cores (Fig. 2). In cores CSJA6 and LZK1, the average abundance of benthic foraminifers is 50 and 33 specimens /50 g, respectively. In Core LZK1, the highest benthic foraminiferal abundance is 718 specimens /50 g at 13 m depth, while in Core CSJA6, the highest of benthic foraminiferal abundance is 385 specimens /50 g at 46.6 m depth. Most of the foraminifers are benthic forms, with planktonic types being <5% in each core.
Benthic foraminiferal species diversity trend is similar to the abundance trend, varying from a low of 20 in Core ZKA4 to 35–46 in cores CSJA6 and LZK1. The middle and upper parts of the Rudong Formation in the three cores have higher foraminiferal abundance and diversity. Of the benthic foraminifers, 115 species in 53 genera have been identified, most of which are hyaline tests. The porcellaneous forms are frequent in some layers, and arenaceous forms are occasionally observed.
The dominant species in the three cores is Ammonia beccarii var., which approaches 50% on average. Other species, such as Ammonia compressiusula, Ammonia ketienziensis, Ammonia pauciloculata, Cribrononion subincertum, Elphidium advenum, Elphidium magellanicum, and Florilus decorus are also present at high frequency. Some species, such as Hazawaia nipponica and Melonis barleeanum, are seldom found (Fig. 11).
Discussion
Based on the occurrences of benthic foraminifers in the cores, three assemblages can be recognized (Fig. 2). In Core CSJA6, for example, the three foraminiferal assemblages are, in ascending order, the Ammonia beccarii-Florilus decorus assemblage, the Ammoina beccarii-Elphidium advenum assemblage, and the Ammonia beccarii-Elphidium magellanicum assemblage (Figs. 2, 12).
The lower parts of the cores (below 42.07 m, 34 m, and 52.9 m for ZKA4, LZK1, and CSJA6, respectively) are characterized by lower foraminiferal abundance and diversity, dominated by Ammonia beccarii var. and Florilus decorus. In addition, Cribrononion subincertum, Elphidium advenum, and Elphidium magellanicum occur in moderate abundance, indicating a hypohaline, low-temperature water environment. The Ammonia beccarii-Florilus decorus assemblage is comparable with the Ammonia beccarii assemblage of the lower part of Bed H I -1 in the South Yellow Sea shelf, both of which have low foraminiferal abundance and diversity (Yang, Reference Yang1985, Reference Yang1993; Yang and Lin, Reference Yang and Lin1996).
The foraminifers are abundant and more diverse in the middle parts of the cores (depth intervals of 3–42.07 m, 12–34 m, and 19.9–52.9 m for ZKA4, LZK1, and CSJA6, respectively), where the shallow-water species Ammoina beccarii var. and Elphidium advenum are dominant. In this interval, the porcellaneous benthic foraminfers are often relatively common. Cavarotalia annectens and Pararotalia nipponica are relatively abundant. For example, the Cavarotalia annectens content is up to 18% at the depth 32.2–32.3 m in Core CSJA6. The benthic foraminifers were typical of warm-water forms. This is corroborated by the relative large size of the foraminiferal tests, which also suggests an influence of high energy water. The Ammoina beccarii-Elphidium advenum assemblage can be correlated with the Ammonia beccarii-Elphidium advenum assemblage of the upper part of Shanghai Formation in the Shanghai region (Wang and Min, Reference Wang and Min1979). It is also comparable with the Ammonia beccarii-Elphidium advenum assemblage of the middle part of the Beijian Formation in the Pearl River Mouth Basin (Yang and Lin, Reference Yang and Lin1996).
The foraminifers observed at the upper part of Core ZKA4 do not indicate a direct influence of sea water in this area. The other two cores, however, suggest that their vicinities were under continued influence of marine environment. The upper parts of LZK1 and CSJA6 have a relatively low benthic foraminiferal abundance and diversity, dominated by Ammoina beccarii var. and Elphidium magellanicum. The assemblage also includes Ammonia compressiuscula, Ammonia ketienziensis angulata, Ammonia pauciloculata, Cribrononion subincertum and Elphidium advenum. The Ammonia beccarii-Elphidium magellanicum assemblage may be correlated to the Ammoina keitienziensis-Astrononion tasmensis assemblage and Elphidium magellanicum assemblage of the upper part of Bed H I -1 in South Yellow Sea Shelf (Yang, Reference Yang1985, Reference Yang1993; Yang and Lin, Reference Yang and Lin1996) based on the common presence of Ammonia beccarii, Elphidium magellanicum, and Ammonia ketienziensis angulata in each fauna.
AMS 14C dating suggests that the studied sediments of the three cores accumulated during the post-glacial period. The three benthic foraminiferal assemblages can be correlated with the faunas of this region in previous work (Min and Wang, Reference Min and Wang1979), which documented the post-glacial transgresstion-regression history, referred to as the “Ammonia transgression” during the Holocene (Wang et al., Reference Wang, Min, Bian and Chen1981).
The Ammonia beccarii-Florilus decorus assemblage points to a weak marine transgression during the early post-glacial period. The Ammoina beccarii-Elphidium advenum assemblage, however, suggests the strongest transgression during the early–middle Holocene, when the warm and relatively deep sea water invaded this region. The Ammoina beccarii-Elphidium magellanicum assemblage corresponds to the late Holocene marine regression, an episode of global sea level drop. Due to the difference in the locations of the studied cores, the results suggest that Core ZKA4 is first out of the influence of the marine water during the late middle Holocene, when the other two cores were still of marine environment during the late Holocene.
Conclusions
The occurrence of abundant foraminifers in three cores drilled in the incised Yangtze paleo-valley revealed post-glacial environmental changes. Three benthic foraminiferal assemblages are present, including the Ammonia beccari-Florilus decorus assemblage during the early post-glacial period, the Ammoina beccarii-Elphidium advenum assemblage during the early-middle Holocene, and the Ammoina beccarii-Elphidium magellanicum assemblage in the late Holocene. The assemblages can be correlated with the “Ammonia marine transgression” during the Holocene (Wang et al., Reference Wang, Min, Bian and Chen1981). The early–middle Holocene benthic foraminiferal assemblage also implies a warm environment because of the occurrence of abundant Cavarotalia annectens and Pararotalia nipponica, and porcellaneous forms. The difference in foraminiferal abundance and diversity suggests that the cores in the modern coastal area are influenced by ocean water since the early post-glacial period, while the upstream core witnessed the transgression only during the middle Holocene. With the global sea level drop, the ocean water retreated from the west since the late middle Holocene and gradually formed the estuary environment in the Yangtze Delta.
Figure 11 SEM photos of the foraminifers from Core CSJA6, Nantong, Jiangsu; Core ZKA4, Yangzhou, Jiangsu; and Core LZK1, Hengsha Island, Shanghai. (1–3) Hazawaia nipponica: (1) ventral view, LZK1, depth 26.9–27.0 m, Reg. No. K1–092; (2) edge view, CSJA6, depth 47.6–47.7 m, Reg. No. K1–094; (3) dorsal view, CSJA6, depth 21.5–21.6 m, Reg. No. K1–093. (4, 5) Melonis barleeanum: (4) side view, CSJA6, depth 23.2–23.3 m, Reg. No. K2–009; (5) edge view, CSJA6, depth 23.2–23.3 m, Reg. No. K2–010.
Figure 12 Down-core variations of main species and assemblages of benthic foraminifers in Core CSJA6.
Acknowledgments
We thank Dr. S. Stukins for arranging the observation on the foraminiferal collections at the Natural History Museum (London). We also thank two anonymous reviewers for their detailed and constructive reviews, which considerably improved the manuscript. This study was supported by the NSFC (Grant No. 41276044), CAS Strategic Priority Project (Grant No. XDPB05), and the Foundation of Geological Survey of China (Nos. GZH201200506, 1212011120173, and 121201004000150021).
