Ke et al.—Post-glacial Foraminifera from the incised Yangtze paleo-valley of China


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., 1988).


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., 1988).


Superfamily Cassidulinacea d’Orbigny, 1839a Family Caucasinidae Bykova, 1959


Genus Fursenkoina Loeblich and Tappen, 1961 Fursenkoina pauciloculata (Brady, 1884) Figure 10.1, 10.2


1884 Virgulina pauciloculata Brady, p. 414, pl. 52, figs. 4, 5. 1965 Fursenkoina pauciloculata; He, Hu, and Wang, p. 84, pl. 6, fig. 7.


Occurrence.—Recent South Pacific; Jiangsu, China (He et al., 1965).


Remarks.—The shorter and wider specimens (Fig. 10.1) repor- ted here are the same as those described by He et al. (1965); the elongate specimen (Fig. 10.2) is referred to those specimens described by Brady (1884), but lacks the short spine in the earliest chamber.


Superfamily Nonionacea Schultze, 1854 Family Nonionidae Schultze, 1854 Genus Nonionella Cushman, 1926


Nonionella jacksonensis Cushman, 1933 Figure 10.5, 10.6


1933 Nonionella jacksonensis Cushman, p. 10, pl. 1, figs. 23a–23c.


1965 Nonionella jacksonensis; He, Hu, and Wang, p. 119, pl. 14, figs. 11a, 11b.


1988 Nonionella jacksonensis; Wang et al., p. 176, pl. 32, figs. 1, 2.


Holotype.—(USNM MO 371678) from Cooper marl, 1.6km (1 mile) south of Moncks Corner, Berkeley Co., S.C. (Cushman, 1933, 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., 1988).


Remarks.—It was reported that there is a slit-like aperture on the base of last chamber (He et al., 1965). 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 0.6–46.1m 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 13m depth, while in Core CSJA6, the highest of benthic foraminiferal abundance is 385 specimens /50 g at 46.6m depth. Most of the foraminifers are benthic forms, with planktonic types being <5% in each core. Benthic foraminiferal species diversity trend is similar to


1994 Virgulina pauciloculata Brady; Jones, pl. 52, figs. 4, 5.


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 ofwhich 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 assem- blage, and the Ammonia beccarii-Elphidium magellanicum assemblage (Figs. 2, 12). The lower parts of the cores (below 42.07 m, 34 m, and


52.9m for ZKA4, LZK1, and CSJA6, respectively) are char- acterized 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, indi- cating 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, 1985, 1993; Yang and Lin, 1996). 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 19.9–52.9m 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


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