Late Quaternary palaeoenvironmental changes documented …Late Quaternary palaeoenvironmental changes ... tant representatives in estuarine environments due to their wide ecological

Journal of Palaeogeography2013, 2(4): 344-361

Palaeogeography

DOI: 10.3724/SP.J.1261.2013.00035

Biopalaeogeography and palaeoecology

Late Quaternary palaeoenvironmental changes documented by microfaunas and shell stable

isotopes in the southern Pearl River Delta plain, South China

Liu Chunlian1, Franz T. Fürsich2, *, Wu Jie1, 3, Dong Yixin1, Yang Tingting1, Yin Jian1

1. Department of Earth Sciences, Sun Yat-Sen University, Guangzhou 510275, China2. Geozentrum Nordbayern, FG Paläoumwelt der Friedrich-Alexander-Universität Erlangen, Loewenichstr. 28, D-91954

Erlangen, Germany3. Guangdong Provincial Key Laboratory of Mineral Resources and Geological Processes, Guangzhou 510275, China

Abstract A high resolution study of sediments, microfaunas (ostracods and foraminifers), and stable isotopes of ostracod shells from core PRD05, sampled from the Da’ao plain of the Pearl River Delta, provides new data about palaeoenvironmental changes during the Late Quaternary. The basal fluvial gravelly sediments of the core, representing the lowest deposits of the Quaternary at the core site, were possibly formed prior to the transgression associated with the last interglacial stage. This fluvial setting changed into a marginal marine setting dur-ing the last interglacial stage, any record of calcareous fossils were destroyed by subsequent dissolution during the last glacial phase, when the upper part of the deltaic sediments experi-enced subaerial oxidation, indicated by a mottled clay layer in the core. The postglacial sea-level rise in the South China Sea began at ~16,700 cal yr B. P. During the first phase of sea-lev-el rise (from ~16,700 to 10,100 cal yr B. P.), a swamp environment developed at the core site. At ~10,100 cal yr B. P., marine waters intruded onto the Da’ao plain and reached the core site through the Modaomen channel. This timing was earlier than in other parts of the Pearl River Delta. Since then, a semi-enclosed estuarine environment developed and was maintained until ~5560 cal yr B. P. During this transgressive interval, short-term environmental fluctuations can be recognized based on microfauna and shell geochemical data. From ~10,100 to 8630 cal yr B. P., the sea-level rose, which was followed by a fall from ~8630 to 8520 cal yr B. P. An expanded transgression occurred between ~8520 and 7900 cal yr B. P. The time intervals from ~8520 to 8200 cal yr B. P. and from ~8080 to 7900 cal yr B. P. were marked by peak transgression. From ~7900 to 5560 cal yr B. P., the core site generally showed a reduced marine influ-ence and enhanced freshwater input. A fluvial environment developed from ~5560 to 3100 cal yr B. P., and was succeeded by an alluvial plain setting.

Key words Late Quaternary, microfauna, shell stable isotopes, palaeoenvironment, Pearl River Delta *

* Corresponding author. Email: [email protected]. Received: 2013-04-19 Accepted: 2013-07-24

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Liu Chunlian et al.: Late Quaternary palaeoenvironmental changes documented by microfaunas and shell stable isotopes in the southern Pearl River Delta plain, South China

1 Introduction

The estuary area is a transitional zone between land and sea, with highly variable water conditions (especially sa-linity fluctuations), to which most marine and freshwater organisms cannot adapt. Among the microfauna, ostracods and, to a far lesser extent, foraminifers are the most impor-tant representatives in estuarine environments due to their wide ecological tolerances. These two groups have proven to be essential for reconstructing Quaternary brackish-water environments (e.g., Ingram, 1998; Mazzini et al., 1999; Anadón et al., 2002; Boomer and Eisenhauer, 2002; Boomer et al., 2003, 2005; Frenzel and Boomer, 2005). The analysis of the composition, species distribution and geochemical characteristics of ostracod and foraminiferal assemblages can provide valuable information on the physical and chemical changes of the water body which should be affected by sea level variations and climatic factors.

Over the past years, some studies have investigated sea-level and environmental changes during the Late Qua-ternary in the Pearl River Delta, and in some of them mi-crofossils were mentioned as supportive evidence (Huang et al., 1982; Xu et al., 1986; Ma et al., 1988; Fang et al., 1991; Lan, 1991, 1996; Li et al., 1991; Zong et al., 2009). However, only sporadic studies on Quaternary microfau-

nas from the Pearl River Delta plain and nearby coastal area have been carried out (Zhao et al., 1987; Yim and He, 1991; Cao, 1998; Huang and Yim, 1998; Wang, 1998; Liu et al., 2008). As most of these studies were based on very sparse sampling and chronostratigraphically are poorly constrained with sporadic dates, they could not provide evidence for recognizing short-term environmental fluctu-ations. Very little attention has been paid to detailed quan-titative microfossil analysis, and stable isotopic studies on shells have never been carried out before.

In the present study, a high-resolution microfaunal analysis, together with stable isotopic analysis of ostracod shells, is performed on core samples collected from the southern plain of the Pearl River Delta. The aim is to re-construct palaeoenvironmental evolution and its relation-ship to sea level and climate changes in the southern plain during the Late Quaternary. Special attention has been paid to the timing of the initial postglacial sea level rise, short-term sea-level fluctuations, and to the timing of peak transgression during the Holocene.

2 Study area

The Pearl River, the largest river in South China and the third largest in China, is primarily formed by the con-

Fig. 1 Location of the studied Core PRD05.

346 JOURNAL OF PALAEOGEOGRAPHY Oct. 2013

fluence of the West-, North-, East-, and Liuxi rivers (Fig. 1), of which the West River is the longest with a channel length of 2214 km (Li et al., 1991). In southern Guang-dong Province, it discharges into the South China Sea through eight main outlets: four outlets in the east (Hu-men, Jiaomen, Hongqili, and Hengmen) and four in the west (Modaomen, Jitimen, Hutiaomen, and Yamen) (Wu and Zhou, 2001; Wu et al., 2006). The Pearl River Delta is a low-lying plain with many small rocky hillocks, de-scending towards the South China Sea and delimited by hills in the east, west, and north. The configuration of the Pearl River Delta is controlled by EW, NW and NE-strik-ing faults (Chen et al., 1995, 2001), which are all covered by Quaternary sediments. The delta formed since the Late Pleistocene (Huang et al., 1982; Chen et al., 1994; Li, 2004). Its Late Quaternary sediments, overlying Pre-Ne-ogene bedrock (sandstones or granites), are generally 25-40 m thick (Huang et al., 1982). Similar to other deltaic basins in East and Southeast Asia, the sedimentary suc-cession generally records two marine transgression cycles, which occurred in the Late Pleistocene and Holocene, re-spectively (Xu et al., 1986; Zhao et al., 1987; Chen et al., 1994; Lan, 1996; Zong et al., 2009). The Late Pleistocene transgression was followed by the Last Glacial, when sea level dropped to -131 m in the South China Sea (Chen et al., 1990). During this period of low sea level, the Pearl River Delta area underwent subaerial weathering, indicat-ed by a layer of widely-distributed mottled clay or fluvial sandy gravel. The Holocene transgression was considered to be more extensive than the Late Pleistocene one, with the coastline shifting northwards far from the present-day coast (Fang et al., 1991). During this transgressive period, most parts of the southern Pearl River Delta were sub-merged and formed a semi-enclosed estuary (Wu et al., 2006). However, due to topographic differences, the tim-ing of marine ingression and regression is not identical in different parts of the delta.

The studied core is located on the present-day southern plain of the Pearl River Delta, close to the Modaomen out-let (Fig. 1), the major outlet of the West River. During the Late Quaternary, the southern plain received over 30 m of sediments, more than the other parts of the delta.

3 Material and methods

Two cores (PRD04 and PRD05) were drilled on the Da’ao Sand of southern plain of the Pearl River Delta, near the Modaomen outlet. Only Core PRD05 (113°11′02″E, 22°31′24″N), 35 m in depth, covers the succession from

the Late Pleistocene to the Holocene and therefore was selected for this study. For the microfossil analyses, 269 samples were collected from 2.51 m to 31.38 m core depth, generally at approximately 10 cm intervals, on average corresponding to ~50 years in the case of Holocene sedi-ments and ~500 years in the case of Pleistocene sediments. No samples were collected from the top and bottom of the core, which have been disturbed by human activities or are composed of gravels.

Dried samples (about 100 g) were disaggregated with tap water and left for 24-48 h, then were boiled in a beaker for about 10 minutes on a hot plate. The fraction larger than 63 mm was separated by wet sieving and dried. A further separation was performed with a 125 mm-mesh sieve. Only the sample fractions larger than 125 mm were used for mi-croscopic observation. Ostracods and foraminifers were handpicked, identified, and counted. The microfossil fre-quencies have been calculated for 100 g of dried sediment.

The oxygen and carbon isotopes were determined on Bicornucythere leizhouensis. This species has been cho-sen because it is one of the most abundant ostracod spe-cies with a wide ecological range, occurring throughout the core section from 24.7 m to 12.4 m. The adult valves of Bicornucythere leizhouensis are bigger than those of other species, so that about 10 specimens were enough for analysis. The selected adult valves were cleaned with de-ionized water, and then treated with anhydrous phosphoric acid at 75℃ and analyzed utilizing a Kiel III device connected to a Finnigan MAT 252 isotope ratio mass spectrom-eter in the Geozentrum Nordbayern at the University of Erlangen, Germany. Isotopic results are reported with re-spect to PDB via the NBS19 standard. The precision is better than 1σ.

For the method of grain size analysis see He et al. (2007).

4 Results

4.1 Lithology and radiocarbon dates

Combining detailed core observation and grain size analysis, Core PRD05 can be divided into 11 lithological units from 34.56 m to the top of the core (bedrock is below 34.56 m) (Fig. 2; Table 1).

Eighteen radiocarbon dates were obtained from organ-ic-rich sediments of the core with conventional 14C dating methods at the Isotope Laboratory of the Guangzhou Insti-tute of Geochemistry, Chinese Academy of Sciences. Two dates (6640±270 yr B. P. at 23.19-23.29 m core depth and

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Fig. 2 Lithological units of Core PRD05 with 14C dates and weight percentages of sediments with a grain size <63 μm.


8640±240 yr B. P. at 20.1-20.20 m core depth) suggest unreasonable ages and were not used. The oldest 14C date is 26,355±550 yr B. P. (30,900±340 cal yr B. P.), obtained from argillaceous silt at 28.97-29.07 m core depth.

However, it has been argued (Yim et al., 1990; Yim, 1999; Zong et al., 2009) that radiocarbon ages from this and similar levels do not represent true ages due to subae-rial weathering during the last glacial period, but that these levels were actually formed under marine conditions dur-ing the last interglacial stage. The gravels at the bottom of the core, the earliest Quaternary sediments at the study site, should then be even older. The youngest 14C date obtained at 4.69-4.81 m of core depth gave an age of 1915±200 yr B. P. (1880±240 cal yr B. P.). The conventional dates and calibrated dates are presented in Figure 2. The calibrated dates are calculated using the 14C-age calibration program CalPal (www.calpal.de). The ages of the lithological unit boundaries and those in the discussion of environmental stages were estimated by extrapolation of sedimentation rates and given as calibrated years.

4.2 Microfossils

The distribution patterns of ostracods and foraminifers are generally similar in Core PRD05 (Figs. 3, 4). Micro-faunas are absent in the lower part of the borehole. The first microfauna are found at 24.7 m core depth, the main taxa include the ostracods Bicorncythere leizhouensis, Neomonoceratina delicate, and Sinocytheridea impressa and the foraminifera Ammonia beccarii var. and Quin‑queloculina seminula. Microfaunal abundance increases

gradually from 24.7 m to 21.7 m, and then decreases from 21.7 m to 20.1 m. The most pronounced peaks occur from 20.1 m to 17.4 m and from 16.9 m to 16.3 m. The abundance decreases again from 16.3 m to 12.4 m. From 12.4 m towards the top of the core only scarce individu-als have been collected. Both ostracods and foraminifers are dominated by euryhaline coastal species. Figures 3 and 4 show the distribution of key ostracod and foraminiferal taxa which represent more than 1% of the total specimens in Core PRD05.

A useful method for reconstructing marginal marine environments is to divide microfaunas into different eco-logical groups (e.g., Mazzini et al., 1999; Ta et al., 2001; Anadón et al., 2002). We also employ this method in this study.

4.2.1 Ostracods

Over 40 ostracod species were identified in Core PRD05. Most species are well known in coastal marine and estua-rine settings of the present-day South and East China Sea. With respect to their ecological ranges and co-occurrence, the ostracod taxa found in the core can be grouped into four types (Table 2). Their ecological distributions are dis-cussed as follows:

Group 1 includes marine ostracod species. They are present in PRD05 in very low abundance, comprising only 2.6% of all individuals. Among them, Macrocypris decora, Mutilus sp., and Stigmatocythere bona are comparatively common, comprising 0.5% to 0.7% of the total ostracods, respectively. The other marine species of the core account

Table 1 Lithological units of Core PRD05

Unit Depth (m) Age (cal yr B. P.) Lithology

k 0-3.30<3100

yellow-grey silt containing plant seeds in the lower part; disturbed sediments from 2.33 m to top of core

j 3.30-10.48 grey to grey-yellow sand and silty sand interbedded with sandy silt

i 10.48-12.42 3100-5560 grey to grey-yellow sand with fine gravels, containing numerous fragments of mol-luscs and barnacles

h 12.42-14.60 5560-7300 sandy silt, with locally abundant molluscsg 14.60-22.69 7300-8690 dark-grey argillaceous silt, a layer of silty sand at 16.66 m

f 22.69-24.78 8690-10,100 dark-grey argillaceous silt, horizontally bedded with streaks of sandy silt and scat-tered concretions, locally with molluscs

e 24.78-26.81 10,100-16,700 a peat layer (about 17 cm in thickness) at the base, grading upwards into dark-grey argillaceous silt with abundant plant remains and scattered brown concretions

d 26.81-27.63

>16,700

mottled silty clayc 27.63-29.12 grey to dark-grey argillaceous siltb 29.12-31.46 yellow-brown fine-grained sand

a 31.46-34.56 gravels with sandy matrix; the diameter of the moderately-rounded pebbles reaches up to 5-8 cm at the base and diminishes to about 2 cm towards the top of the interval

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for less than 50 individuals per 100 g sediment. These spe-cies are typically found in the middle and outer shelf area in the present-day East China Sea and South China Sea in euryhaline waters (Zhao et al., 1986; Cai, 1988; Wang

et al., 1988; Zhao and Wang, 1988; Liu et al., 2002). The occurrence of most of them at the core site might result from transportation by marine currents.

Group 2 consists of those ostracod species being able

Table 2 Ostracod and foraminiferal taxa from Core PRD05 arranged in ecological groups. In each group the taxa are ranked in de-creasing relative abundance

Ostracod taxa Foraminiferal taxa

Group 1Mutilus sp. (0.7%)Stigmatocythere bona (0.6%)Macrocypris decora (0.5%)Paijenborchella miurensis (0.2%)Paracytherois angusta (0.2%)Stigmatocythere rosemani (0.1%)Bythoceratina sheyangensis (0.1%)Propontocypris clara (0.1%)Cytheropteron miurense (0.05%)Semicytherura sp. (0.03%)Loxoconcha viva (0.03%)Paracytherois oblonga (0.01%)Cythere omotenipponica (0.01%)Neonesidea elegans (0.004%)

Group 2Pistocythereis bradyformis (6.2%)Neosinocythere elongata (4.7%)Spinileberis quadriaculeata (3.3%)Sinocythere sinensis (2.8%)Alocopocythere kendengensis (1.7%)Bicorncythere bisanensis (1.6%)Keijella hodyii (1.3%)Hemicytherura biannularis (0.79%)Loxoconcha tarda (0.26%)Munseyalla pupilla (0.09%) Copytus posterosulcus (0.07%)Aurila cymba (0.06%)Spinileberis sinensis (0.04%)Cytherois leizhouensis (0.04%)Loxoconcha sp. (0.04%)Callistocythere multirugosa (0.01%)Loxoconcha ocellata (0.005%)

Group 3Sinocytheridea impressa (26.7%)Bicorncythere leizhouensis (23.6%)Neomonoceratina delicate (23.5%)Perissocytheridea sp. (0.21%)Perissocytheridea japonica (0.17%)Leptocythere ventriclivosa (0.07%)Pontocypris euryhalina (0.03%)

Group 4Heterocypris sp. (0.07%)Candona sp. (0.05%)Ilyocypris bradyi (0.03%)Ilyocypris sp. (0.01%)Caspiolla sp. (0.01%)Eucypris sp. (0.003%)

Group 1Massilina penglaiensis (0.6%)Lagena hispidula (0.09%)Guttulina pacifica (0.04%)Spiroloculina robusta (0.01%) Quinqueloculina tropicalis (0.01%)Fissurina laevigata (0.001%)

Group 2Quinqueloculina seminula (10.1%)Elphidium advenum (6.5%)Cavarotalia annectens (4.2%)Ammonia pauciloculata (3.6%) Protelphidium granosum (3.1%)Cribrononion asiaticum (2.5%)Massilina laevigata (1.2%)Elphidium hispidulum (0.8%)Cribrononion subincertum (0.2%)Quinqueloculina lamarckiana (0.09%)Pararotalia nipponica (0.05%)Quinqueloculina contorta (0.02%)Triloculina rotunda (0.01%) Quinqueloculina sabulosa (0.005%)Rosalina bradyi (0.003%)

Group 3Ammonia beccarii var. (48.7%)Quinqueloculina akneriana rotunda (10.5%)Ammonia tepida (6.5%)Nonion akitaense (0.7%)Cellanthus craticulatus (0.2%)Nonion anomalinaidea (0.1%) Ammonia convexidorsa (0.04%)Ammonia koeboeensis (0.02%)Ammonia sp. (0.01%)


to withstand a wider range of salinity, from polyhaline to poly-euryhaline. They are moderately abundant in PRD05, comprising 22.9% of the total ostracods. This group is dominated by Pistocythereis bradyformis (6.2% of the to-tal ostracods), Neosinocythere elongata (4.7%), Spinileb‑eris quadriaculeata (3.3%), Sinocythere sinensis (2.8%), Alocopocythere kendengensis (1.7%), Bicorncythere bisanensis (1.6%), and Kejella hodgii (1.3%). They usually prefer salinity values above 25‰ and water depth from 20 to 50 m, although some of them can also live under coastal conditions (Zhao et al., 1986; Wang et al., 1988; Zhao and Wang, 1988; 1990; Cai, 1993).

Group 3 includes the most strongly euryhaline coastal species, which can tolerate a wide range of salinity and very shallow water depth. They are the major ostracod elements of the core and comprise 74.3% of the total in-dividuals. Strikingly predominant species include Sino‑cytheridea impressa (26.7%), Bicorncythere leizhouensis (23.6%), and Neomonoceratina delicata (23.5%). These three species occur throughout the core section from 24.7 to 12.4 m. Sinocytheridea impressa is a very well-known euryhaline species, widely distributed in recent and Qua-ternary sediments along the coast of China (Zhao and Han, 1980; Zhao, 1987; Wang et al., 1988; Zhao and Wang, 1990; Cao, 1998; Liu et al., 2002). It can tolerate salinity ranges from 2‰ to euryhaline and a water depth of less than 20 m. Neomonoceratina delicata is also a typical shal-low-water species off coastal area in the South China Sea (Cai, 1988; Zhao and Wang, 1988, 1990). There are only a few studies on the distribution of Bicorncythere leizhouen‑sis. It is here considered as a coastal species because of its common co-occurrence with Sinocytheridea impressa and Neomonoceratina delicata in the core. The remaining spe-cies of this group are only sporadically found in the core.

Group 4 consists of freshwater ostracods. Elements of this group occur sporadically and as very few valves in the studied core, comprising about 0.2% of the total os-tracods. They are only found in samples from the upper part of the core, where few other ostracods have been col-lected. These genera are adapted to live in freshwater en-vironments but also tolerate slightly brackish conditions (De Deckker, 1981; Hou et al., 1982, 2002; Anadón et al., 1986; Zhao, 1987; Neale, 1988; Mazzini et al., 1999).

4.2.2 Benthic foraminifers

The foraminiferal fauna consist of a total of 30 species. No planktic foraminifers were found. In modern sediments of the South and East China Sea, the distribution of many benthic species shows a strong relationship with water

depth and salinity (e.g., Wang et al., 1980, 1988; Li, 1985; Li and Bian, 1989). According to their ecological prefer-ences and co-occurrence, the encountered benthic species can be included in three groups (Table 1), which approxi-mately correspond to Group 1, 2, and 3 of the ostracods.

Group 1 consists of marine species, which occur spo-radically in very low abundance, accounting for about 0.8% of the total foraminifers in the core. Only Massilina penglaiensis shows a higher abundance, reaching a maxi-mum of 116 individuals per 100 g sediments at 18.92 m core depth. Similar to the marine ostracod species in the core, they are, based on their ecological requirements, in-terpreted to be mostly allochthonous elements.

Group 2 is composed of foraminiferal species, whose ecological ranges correlate with those of ostracod Group 2. This group comprises about 32.4% of the total foramin-ifers in the core. The dominant species include Quinque‑loculina seminula (10.1% of all individuals of foramini-fers), Elphidium advenum (6.5%), Cavarotalia annectens (4.2%), Ammonia pauciloculata (3.6%), Protelphidium granosum (3.1%), Cribrononion asiaticum (2.5%), and Massilina laevigata (1.2%). They occur in most samples from 24.7 to 12.4 m core depth. They are also common species along the present-day Southeast China Sea, most-ly distributed in outer parts of the inner shelf to the middle shelf with water depth ranging from 20 m to 50 m and a salinity varying between polyhaline and eupolyhaline (Wang et al., 1988).

Group 3 includes coastal marine species, mainly lim-ited to shallow water depths of 20 m or less. As euryhaline taxa they can tolerate waters of low salinity. This group accounts for 66.9% of the total foraminifers. Ammonia beccarii var. (48.7%), A. tepida (6.5%), and Quinquelo‑culina akneriana (10.5%) are the predominant species. These species, particularly Ammonia beccarii var., are very broadly distributed in modern coastal brackish envi-ronments of the South China Sea, East China Sea, Yellow Sea, and Bohai (Wang et al., 1980, 1988; Li, 1985, 1994; Li and Bian, 1989; Zhu et al., 1998). They live in water depths of 0 to 50 m, but largely occur at a depth of less than 20 m. Ammonia beccarii var. is the most abundant species and occurs in all samples from 24.7 m to 12.4 m core depth. The highest abundance is 3180 specimens per 100 g sediment (at 18.82 m core depth). A. tepida and Q. akneriana are found in most samples. The remaining spe-cies of this group are rare.

4.3 Stable isotope data of ostracod valves

In this study, δ13C and δ18O isotope analyses were per-

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formed on valves of Bicornucythere leizhouensis, which is one of the most abundant species in PRD05. By meas-uring a single species, possible interspecific differences in isotope composition resulting from vital effects can be avoided. The isotope results of 64 samples are shown in Figure 5. δ18O shows a comparatively small range of val-ues between -7.87‰ and -3.89‰, with an average value of -5.79‰. The δ13C values fluctuate between -13.34‰ and -8.54‰, with an average value of -10.34‰, corre-sponding to a relative enrichment in 12C. δ13C and δ18O show a co-variant trend for most parts of the core (r=0.59), particularly for the core depth below 15.5 m (r=0.71). This co-variation between δ13C and δ18O suggests that the vari-ation in isotopic compositions corresponds to variations in salinity (Ingram et al., 1996).

5 Palaeoenvironmental reconstruction

By combining lithological, microfauna, and stable iso-topic data of ostracod shells from Core PRD05, palaeoen-vironmental changes largely related to sea-level fluc-tuations during the Late Pleistocene to Holocene can be reconstructed. The periods of the Holocene transgression are highlighted.

5.1 Stage I: Pre-Holocene (core depth: 34.56-26.81 m; before ~16,700 cal yr B. P.)

No microfossils were found in this core interval. Based on lithological characteristics, it can be divided into three phases.

5.1.1 Substage I1: 34.56-29.12 m core depth (before ~31,000 cal yr B. P.)

The basal coarse sediments, overlying bedrock, repre-sent the earliest Quaternary record in the study area. This fluvial sand-gravel interval is usually 2-7 m thick, reach-ing a maximum of 11 m in the Pearl River Delta area (Xu et al., 1986). In the studied core, its thickness of 5.44 m is moderate, corresponding to the older terrestrial unit (T2) of Zong et al. (2009). The sediments were deposited in a palaeo-valley, with initially very high energy conditions, which diminished later as is demonstrated by the reduction in grain size. No radiocarbon dates were obtained from this core interval, but a relative age of older than ~31,000 cal yr B. P. can be assumed by extrapolation from the overly-ing sediments. In previous work, ages between 30,000 and 40,000 yr B. P. were obtained for this sand-gravel interval from other parts of the delta and it is usually considered to have been deposited during the early phase of the last

interglacial stage (Xu et al.,1986; Wen et al., 1997). Zong et al. (2009) considered this terrestrial unit as having been deposited prior to MIS 5.

5.1.2 Substage I2: 29.12-27.63 m core depth (from ~31,000 to ~21,700 cal yr B. P.)

This core interval is still unfossiliferous, but litholo-gies change to argillaceous silt. This suggests a change of depositional conditions. Rare earth elements (REE) data for this fine-grained interval indicate an estuary environ-ment, with a relatively high åREE (average value: 234.2 ppm) and a clear enrichment of light rare earth elements (LREE) relative to heavy rare earth elements (HREE) (Liu et al., 2011). We deduce that this core interval formed un-der at least brackish conditions during the last interglacial stage and it should correspond to the older marine unit (M2) of Zong et al. (2009). The lack of any fossils might be an artifact produced by dissolution of any carbonate skeletal grains during subsequent subaerial exposure.

Three organic-rich samples were taken at 27.36 m, 28.39 m and 29.02 m core depth, respectively from this interval of PRD05. They provided conventional radio-carbon ages of 17,968±430 yr B. P. (21,460±630 cal yr B. P.), 18,635±450 yr B. P. (22,350±560 cal yr B. P.) and 26,355±550 yr B. P. (30,900±340 cal yr B. P.), respec-tively. Similar ages have been obtained in this marine unit from other sites of the Pearl River Delta (Huang et al., 1982; Li et al., 1991; Lan, 1996; Zong et al., 2009). The age of this marine sequence is under debate. Some authors dated it as belonging to MIS 3 (e.g., Xu et al., 1986; Zhao et al., 1987; Wen et al., 1997). The equivalent marine sedi-ment, the Gehu marine sequence, with an age between 20,000 and 40,000 yr B. P., occurring along the eastern coast of China, has also been placed in MIS 3 (Chen, 1992; Yu et al., 2005; Wang et al., 2008, 2008). Other authors argued that these dates cannot reflect true ages due to suba-erial weathering during the last glacial period and that this marine unit should be assigned to MIS 5, a period with a sea-level highstand comparable to today (Yim et al., 1990; Yim, 1999; Zong et al., 2009). There exists a discrepancy of up to tens of meters in estimates of sea level during MIS 3. Global sea level in MIS 3 inferred from deep-sea oxygen isotope series and coral reef records was as low as around −80 m (e.g., Chappell et al., 2002; Yokoyama et al., 2007). However, marine records likely formed during MIS 3 have been also reported from other coastal areas of the world (e.g., Belluomini et al., 2002; Hanebuth et al., 2006; Gracia et al., 2008) and it has been proposed that the sea level during MIS 3 might have been much higher


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(e.g., Liu, 1997; Belluomini et al., 2002; Yang et al., 2004; Huang and Cai, 2007; Gracia et al., 2008). After studying numerous relic records of sea-level stands along the coasts from the Bohai to the South China Sea, Liu (1997) suggested that sea level between 20,000 and 40,000 yr B. P. was very likely close to its present position. According to Shi and Yu (2003), precipitation and temperature during late MIS 3 were higher than today in China and, corre-spondingly, a large transgression occurred in delta areas of the Yangtze River and the Pearl River.

If the dates obtained from PRD05 were acceptable, this interval would belong to MIS 3. However, it is possible that these ages are too young as argued by Zong et al. (2009). In our opinion additional independent chronologi-cal controls are required to constrain the exact ages of this marine sequence.

We estimate that the marine waters intruded the core site mainly through the easterly outlets, because the Modaomen channel probably had not yet formed at this time. The oldest 14C date for the fluvial sediments of the Modaomen channel is ~20,300 yr B. P. (Chen et al., 1994).

5.1.3 Substage I3: 27.63-26.81 m core depth (from ~21,700 to ~16,700 cal yr B. P.)

This substage is characterized by a mottled clay layer, which is widely distributed in the Pearl River Delta and most likely formed by subaerial oxidation of the sedi-ments (Lan, 1991, 1996; Huang et al., 1997; Wen et al., 1997; Dong et al., 2007; Huang and Cai, 2007; Zong et al., 2009). Along palaeo-river channels in the Pearl River Del-ta area, a layer of sand and gravel was deposited instead of this weathered clay, which corresponds to the younger ter-restrial unit (T1) of Zong et al. (2009). This layer has been usually considered to have been formed during the last glacial maximum (Xu et al., 1986; Huang and Cai, 2007). It approximately corresponds to MIS 2 and can be corr- elated with the first “hard mud” unit in the Yangtze River Delta (Wang et al., 2008). It was estimated that during this period the sea level fell to around -130 m in the South China Sea, where palaeoshoreline records were found (Chen et al., 1990). However, Huang et al. (1995) argued that the lowest sea level of the last glacial maximum might have been at about -80 m, comprehensively considering various records, including tectonic subsidence. In the East China Sea, Feng (1983) suggested the lowest sea level during the last glacial maximum was 140-160 m below present level.

During this time of sea-level lowstand, the region from the Pearl River mouth to the northern South China Sea

was exposed and experienced continental weathering. The weathered sediments usually have a thickness of 1-3 m, with a maximum of 5 m in the Pearl River Delta. The mot-tled clay layer in the core site is < 1 m thick, probably due to the topographically lower position compared to other parts of the delta.

5.2 Stage II: Early Holocene (core depth: 26.81-24.7 m; from ~16,700 to ~10,100 cal yr B. P.)

This core interval is characterized by a 17 cm-thick peat layer at the base and by dark-grey argillaceous silt with abundant plant remains higher in the interval. No mi-crofossils were observed. This facies can be interpreted as a swamp deposit that was formed at the onset of the postglacial sea-level rise. The beginning of the postglacial transgression in the Pearl River estuary area has been pre-viously estimated at about 12,000 yr B. P. by some authors (e.g., Xu et al., 1986; Li et al., 1991), but with no reliable evidence. In this study, a 14C age of 13,380±220 yr B. P. (16,450±560 cal yr B. P.) was obtained from the peat sam-ple close to the base of this interval, at 26.72 m core depth. The peat deposition has been taken as reliable evidence of a warmer climate (Kim and Kennett, 1998). This sug-gests that the postglacial sea-level rise might correspond to the formation of the peat sediments, at ca. 16,700 cal yr B. P. (there are about 10 cm peat below the 14C measure-ment point). These results approximately agree with that obtained by Chen et al. (1990), who demonstrated that the last glacial phase should have ended in the South China Sea at 13,700±600 yr B. P. (non-calibrated age). A simi-lar date (13,000 to 14,000 yr B. P., non-calibrated age) for the onset of the postglacial transgression has also been obtained for the Yangtze River Delta area (Li and Zhang, 1996).

For the Sunda shelf, a slightly older age (14,600 yr B. P.) is given for the onset of rapid sea-level rise (Hanebuth et al., 2000). Kienast et al. (2003) arrive at a similar figure (14,700 yr B. P.) for the northern South China Sea.

5.3 Stage III: Holocene transgression (core depth: 24.7-12.4 m; from ~10,100 to 5560 cal yr B. P.)

At around 10,100 cal yr B. P., the rate of sea-level rise rapidly increased and a brackish estuary with abundant microfaunas, strikingly dominated by euryhaline species, developed and persisted at the core site until 5560 cal yr B. P. During this transgressive interval, several substages corresponding to short-term environmental fluctuations can be recognized based on the composition and abundance of


microfossils and stable isotope data (Fig. 5). These changes in the microfauna record are thought to primarily rep-resent changes in relative sea level and salinity, although other environmental factors such as shifting current sys-tems, fluctuations in river discharge, and changing topog-raphy might have also played some role.

5.3.1 Substage III1: 24.7-21.7 m core depth (from ~10,100 to 8630 cal yr B. P.)

In the interval immediately above the freshwater swamp sediments, microfaunas record a rapid rise in sea-level. At about 10,100 cal yr B. P., marine waters began to intrude the Da’ao area, where the core site is located, through the Modaomen channel (He et al., 2007). The first evidence of microfaunas within the core occur at 24.7 m core depth. From 24.7 to 23.7 m, the microfaunal abundance is very low, with 192 specimens per 100 g sediments on average for foraminifers and 251 for ostracods. Foraminifers of Group 2 are more abundant (59.5%) than those of Group 3 (33.3%). Ostracods of Group 2 show the highest rela-tive abundance within the core (34.5%), although lower than that of Group 3 (60.1%). Marine species, both of fora-minifers and ostracods, are in low abundance, usually less than 50 specimens per 100 g sediments, but their relative abundance is the highest within the core, with 7.2% and 5.4%, respectively. This interval marks the first stage of the Holocene transgression, when the study area began to develop into a shallow brackish estuary, and became colo-nized by euryhaline and marine species.

From 23.7 m upwards, microfaunal abundance gradu-ally increases with the expanding transgression. Fo-raminiferal abundance peaks at 1571 specimens per 100 g sediment (average: 613 specimens); ostracod abundance peaks at 2462 specimens (average: 915 specimens). The increase in the percentage of taxa of coastal groups in both ostracods and foraminifers is much higher than that of taxa from Group 2, which, together with marine species, show a decrease in relative abundance. The high-stress, brack-ish, shallow-water environment limited their develop-ment. The δ18O and δ13C values generally show an increase during this interval, both reaching peaks at 21.7 m, with -3.89‰ and -8.71‰, respectively. This indicates increas-ing salinity due to intrusion of marine waters.

These data can be compared with the curves of the Holocene relative sea-level change proposed by several authors for the Pearl River Delta area (Fig. 6) (Fang et al. 1991; Li et al., 1994; Zong, 2004). It has been suggested that a rapid rise in relative sea level occurred during the Early Holocene, when the sea level rose at a rate of about

21.6 mm/yr (Fang et al., 1991). At other localities along the southeast coast of China, a similar trend in Early Holo-cene sea level rise has been recorded (Zong, 2004).

5.3.2 Substage III2: 21.7-20.1 m core depth (from ~8630 to 8520 cal yr B. P.)

During this interval, microfaunas, particularly ostra-cods, decrease to an average abundance of 537 specimens (ostracods) and 604 specimens (foraminifers) per 100 g sediments. Members of Group 2 decrease more obviously in abundance than members of the coastal group, which become strongly dominant with relative abundances of up to 85.3% and 74.1% for foraminifers and ostracods, re-spectively. Among coastal foraminifers, Ammonia becca‑rii var. strongly dominates, reaching an average of 67.4%. Such changes may be linked to decreasing water depth, accompanied by a decrease in salinity. This is supported by a sharp decrease of the δ18O and δ13C values, from -3.89 to -8.92‰ and from -8.71 to -12.33‰, respectively. Fang et al. (1991) reported that there was a short episode of seal-level standstill or fall between 7400 and 7100 yr B. P. (non-calibrated age), to which this substage of Core PRD05 is thought to be comparable.


From 20.1 m to 17.4 m, the microfauna is very abun-dant. Three phases can be distinguished: From 20.1 m to 19.6 m, a sharp increase in microfaunal abundance is observed; 1626 specimens in the case of foraminifers and 1856 specimens in the case of ostracods per 100 g sedi-ment on average. From 19.6 m to 18.5 m, microfaunal abundance reaches the highest value. Foraminifers reach a peak value of 5029 specimens, with an average value of 4123 specimens per 100 g sediments; ostracods reach

Fig. 6 Sea-level curve of the South China coast during the Holocene (redrawn from Li et al., 1994). Dashed lines represent possible change limits of the sea level.

357Vol. 2 No. 4


a peak value of 5486 specimens, with an average value of 2753 specimens per 100 g sediments. Among foraminifers, species of Group 2 show an obvious increase in relative abundance, while coastal species, particularly Ammonia beccarii, decrease in relative abundance. Marine foramini-fers show the highest abundance within the core (up to 116 specimens per 100 g sediments), although their relative abundance is low. From 18.5 m to 17.4 m, the microfauna is still abundant: 2374 specimens (foraminifers) and 2422 specimens (ostracods) per 100 g sediments. Although the abundance values are smaller than those during the previ-ous phase, the relative abundance of foraminifers and os-tracods of Group 2, particularly the foraminifera, distinctly increase.

These microfaunal results suggest that salinity and depth increased with a renewed sea-level rise at about 8520 cal yr B. P., which favoured the development of an abundant microfauna. This environment persisted until ~8200 cal yr B. P. Isotopic data correlate well with the mi-crofaunal results. δ18O and δ13C show a positive shift and then stay at comparatively high values until 17.4 m core depth, implying an increase in salinity due to an enhanced marine influence. This interval records the peak marine in-trusion in the study area.

5.3.4 Substage III4: 17.4-16.9 m of core depth (from ~8200 to 8080 cal yr B. P.)

A short interval of reduced water depth is evidenced by sharply decreased microfaunal abundance, with an aver-age of 945 foraminifer specimens and 626 ostracod speci-mens per 100 g sediments. Among foraminifers, Ammonia beccarii var. shows a prominent increase in relative abun-dance. This environmental change seems to have had the same effect on ostracods of Group 2 and 3, which decrease in a similar way, with their relative abundance showing lit-tle variation. In contrast to the trend of the microfauna, sta-ble isotope values show a positive shift, reaching -4.35‰ for δ18O and -8.54‰ for δ13C, which indicates an increase in salinity. This might be related to the dry climate, which prevailed during this period of regression and resulted in high evaporation rates.

5.3.5 Substage III5: 16.9-16.3 m core depth (8080 to 7900 cal yr B. P.)

Microfaunal abundance shows peak values again in this interval. Foraminifers increase up to 2176 specimens (maximal value: 3968) and ostracods increase up to 2220 specimens (maximal value: 5742) per 100 g sediments. Species of Group 2 increase again both in the case of fora-

minifers and ostracods. Particularly in foraminifers, rela-tive abundance of Group 2 taxa (54%) is higher than that of coastal species (45%); Ammonia beccarii var. shows a sharp decrease in abundance, accompanied by an increase in species of Group 2. Marine species are more common, even though they are allochthonous. This suggests an in-crease in water depth, possibly related to a new marine transgression following the previous short regressive pe-riod (see also Wei et al., 2011). The δ18O and δ13C values, although decreasing, are comparable to those of the previ-ous transgression. This means that the climate turned hu-mid again and water salinity was mainly influenced by the extent to which marine and fluvial waters became mixed.

As suggested by both the microfauna and stable isotopic data, the maximum marine transgression in the study area took place from 8520 to 7900 cal yr B. P., although a short-term regression occurred between ~8200 to 8080 cal yr B. P. The striking dominance of euryhaline taxa suggests a shallow, brackish estuary with a water depth of less than 20 m. This interval most likely corresponds to the Mid-Hol-ocene sea-level highstand, which can be identified along the southeastern coast of China (Zong, 2004), although differing in height and timing at different localities. The occurrence of the sea-level highstand seems to be earlier at the core site than in other parts of the Pearl River Delta. Thus, Wei et al. (2011) assumed maximum transgression around 6000 yr B. P. (non-calibrated) for the Pearl River delta as a whole.


During this time interval, other parts of the Pearl River Delta were marked by the peak Holocene marine trans-gression (e.g., Xu et al., 1986; Fang et al. 1991; Li et al., 1991; 1994; Wei et al., 2011). In contrast, a general de-crease in microfaunas is observed at the core site, although there is a small increase in the middle part (from 15.6 m to 14.3 m). It seems that an unstable environment developed at the core site. From 16.3 m to 15.6 m there is a sharp decrease in microfaunal abundance (714 foraminifer and 395 ostracod specimens per 100 g sediments). Both δ18O and δ13C show a negative shift and δ18O reaches the lowest value (-7.87‰) within the core, implying reduced salinity. From 15.6 m to 14.3 m, there is a small increase in abundance, particularly of foraminifers (up to 1332 speci-mens per 100 g sediments). Taxa of Groups 2 and 3 in-crease, and in the case of the latter more strongly. Ostra-cods do not show an obvious increase in abundance, but elements of Group 2 are more abundant than before. The


isotopic data show higher values than those in the previous interval, indicating an increase in salinity, which should be linked to an enhanced marine influence. From 14.3 m up-wards, microfossils clearly decrease. Ostracods are low in abundance with 191 specimens per 100 g sediment. Most species are represented only by a few reworked valves. Foraminifers are overwhelmingly dominated by coastal species (reaching 92%), especially by Ammonia beccarii var. and A. tepida (78% and 11.2%, respectively). δ18O and δ13C show little positive correlation. δ18O values exhibit small variations, whereas δ13C values fluctuate strongly and show a large negative shift to -13.34‰ (at core depth 12.87 m). This may correspond to a period when an en-hanced freshwater influx with increased organic matter re-sulted in the enrichment of 12C and a distinctly low salinity.

According to He et al. (2007), the southern part of the Da’ao plain, where the studied core is located, experienced a higher sedimentation rate with an average value of ~0.9 cm/yr from ~9000 to 7000 yr B. P. (~10,100 to 7850 cal yr B. P.). They suggested the existence of a turbid water mass with dense muddy material, carried into this area by tidal currents. This rapid sedimentation might have altered the topography at the core site. From ~7900 cal yr B. P. onwards, marine influence gradually decreased and run off influence increased. This is further supported by the increase in grain size of sediments from 14.3 m upwards. Probably starting at that time, the number of small tribu-taries joining the West River increased, which enhanced water energy and river influence.

5.4 Stage IV: Mid- to Late Holocene (core depth: 12.4-0 m; since ~5560 cal yr B. P.)

From 12.4 m to 3.3 m core depth, barren sands are pre-sent, with sporadic small pebbles and abundant fragments of molluscs and barnacles at the bottom. From 3.3 m on-wards, the sediment changes to argillaceous silt. Scattered reworked valves of euryhaline ostracods are present in a few samples. Fresh- to brackish-water ostracods, which rarely occur elsewhere in the core, are sporadically present from 4.7 m to the core top, but occur in low abundance. Some characean oogonia occur at the core top. A few re-worked tests of Ammonia beccarii are also present. Such deposits indicate that, starting from ~5560 cal yr B. P., the study area was predominantly affected by runoff input, but with occasional tidal influence. A sandy fluvial depo-sitional environment developed from ~5560 to 3100 cal yr B. P., then changed into an alluvial plain setting, with a very low salinity and little marine influence. This development differs from that of most parts of the Pearl River

Delta, which were still submerged and influenced by ma-rine waters (Fang et al., 1991; Li et al., 1994). It has even been considered that the sea level reached its peak at 3000 cal yr B. P. (Zong, 2004). This discrepancy possibly results from different topographic conditions; the core site was strongly affected by freshwater from the West River dur-ing this time.

6 Conclusions

This integrated study of the lithological, microfaunal and ostracod stable isotopic records allows us to recon-struct, in detail, palaeoenvironmental evolution during the late Quaternary at the site of Core PRD05 in the Pearl River Delta.

Gravel deposits at the bottom of the core most likely were formed prior to the transgression of the last intergla-cial stage. They represent a fluvial environment with water energy decreasing upwards and are the earliest evidence of Quaternary sedimentation at the core site. Subsequently marginal marine conditions became established. The fine-grained sediment became decalcified during the last glacial episode when it was subaerially exposed, which is shown by a mottled clay layer in the core. The onset of the post-glacial sea-level rise in the South China Sea was no later than ~16,700 cal yr B. P. During the first phase of sea-level rise (from ~16,700 to 10,100 cal yr B. P.), a swamp envi-ronment developed at the core site. At around 10,100 cal yr B. P., when sea-level rapidly increased, marine waters intruded the Da’ao plain and reached the core site through the Modaomen channel. This occurred much earlier than in other parts of the Pearl River Delta. Since then, a semi-en-closed estuary developed, with a dominance of euryhaline microfaunas, which persisted until ~5560 cal yr B. P. Dur-ing this transgressive interval, short-term environmental fluctuations can be recognized based on microfaunal and stable isotope data. The rise in sea-level from ~10,100 to 8630 cal yr B. P. was followed by a sea-level fall accompa-nied by a decrease in salinity and water depth from ~8630 to 8520 cal yr B. P. An extended transgression occurred between ~8520 and 7900 cal yr B. P. The time intervals from ~8520 to 8200 cal yr B. P. and from ~8080 to 7900 cal yr B. P. mark the peak transgressions, during which the microfauna reached the greatest abundance. From ~7900 to 5560 cal yr B. P., the core site generally showed a re-duced marine influence and enhanced freshwater input, in contrast to other parts of the Pearl River Delta. A fluvial environment developed from ~5560 to 3100 cal yr B. P. and was succeeded by an alluvial plain setting.

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Changes in salinity as evidenced by microfaunal com-position as well as by stable oxygen isotopes were not necessarily connected only to relative changes in sea level and/or transgressions/regressions, but might have also been influenced by changing current patterns, shifting depocenters, and fluctuations in fluvial discharge. Still, at the time scales considered here (hundreds to thousands of years) relative changes in sea level should have been of overriding importance.

Acknowledgements

This research was supported by the Natural Science Foundation of China (Grant No. 40872024 and No. 40331007) and by travel grants within the framework of the Project-based Personnel Exchange Programme of the DAAD (Deutscher Akademischer Austauschdienst) and CSC (China Scholarship Council). We would like to thank Prof. Dr. Wu Chaoyu at the Center for Coastal Ocean Sci-ence and Technology Research, Sun Yat-Sen University, for supporting the drilling of the core and numerous dis-cussions, and Manja Hethke and Matthias Alberti, Erlan-gen University, for critical reading of the manuscript. We also acknowledge the constructive criticism of several anonymous reviewers.

References

Anadón, P., De Deckker, P., Julià, R., 1986. The Pleistocene lake deposits of the NE Baza Basin (Spain): Salinity variations and ostracod succession. Hydrobiologia, 143: 199-208.

Anadón, P., Gliozzi, E., Mazzini, I., 2002. Paleoenvironmental re-construction of marginal marine environments from combined paleoecological and geochemical analyses on ostracods. In: Hol-mes, J. , Chivas, A., (eds). The Ostracoda: Applications in Qua-ternary Research. Geophysical Monograph, 131: 227-247.

Belluomini, G., Caldara, M., Casini, C., Cerasoli, M., Manfra, L., Mastronuzzi, G., Palmentola, G., Sanso, P., Tuccimei, P., Vesica, P.L., 2002. The age of Late Pleistocene shorelines and tectonic activity of Taranto area, Southern Italy. Quaternary Science Re-views, 21: 525-547.

Boomer, I., Eisenhauer, G., 2002. Ostracod faunas as palaeoenviron-mental indicators in marginal marine environments. In: Holmes, J., Chivas, A., (eds). The Ostracoda: Applications in Quaternary Research. Geophysical Monograph, 131: 135-149.

Boomer, I., Horne, D. J., Slipper, I. J., 2003. The use of ostracods in palaeoenvironmental studies, or what can you do with an ostra-cod shell? Paleontological Society Paper, 9: 153-179.

Boomer, I., Grafenstein, U., Guichard, F., Bieda, S., 2005. Modern and Holocene sublittoral ostracod assemblages (Crustacea) from

the Caspian Sea: A unique brackish, deep-water environment. Pal-aeogeography, Palaeoclimatology, Palaeoecology, 225: 173-186.

Cai, H., 1988. Ostracoda in sediments from the northern continental shelf of the South China Sea. Tropic Oceanology, 1: 19-27.

Cai Huimei, 1993. A study on the paraecology of depositional Os-tracoda in the northern and central areas of Taiwan strait. Tropic Oceanology, 12: 71-78 (in Chinese with English abstract).

Cao Meizhen, 1998. Ostracods from the Quaternary Kengkou For-mation in Liyumen, Hongkong. In: Li Zuoming, Chen Jinhua, He Guoxing, (eds). Research on palaeontology and stratigraphy in Hongkong. Beijing, Science Press. 171-183 (in Chinese).

Chappell, J., 2002. Sea level changes forced ice breakouts in the Last Glacial cycle: new results from coral terraces. Quaternary Sci-ence Reviews, 21: 1229-1240.

Chen Xinshu, Bao Liyan, Chen Junren, Zhao Xitao, 1990. Discovery of lowest sea level in Late Quaternary at the continental shelf off Pearl River Mouth. Journal of Tropical Oceanography, 9: 73-77 (in Chinese with English abstract).

Chen Guoneng, Zhang Ke, He Xikun, Chen Fanshen, Nian Hong, 1994. Paleogeographic evolution of the Pearl River Delta since the Late Pleistocene. Quaternary Sciences, 1: 67-74 (in Chinese with English abstract).

Chen Guoneng, Zhang Ke, Chen Huafu, He Xikun, 1995. A study on the neotectonics of the faults in the Pearl River Delta area, South China. Journal of Seismology, 15: 16-21 (in Chinese with English abstract).

Chen Ronghua, 1992. Quaternary transgressions along the coast of Zhejiang. Acta Oceanologica Sinica, 14: 76-85 (in Chinese).

Chen Weiguang, Zhan Hongmei, Chang Yu, Lu Banghua, 2001. The rate of Late Quaternary vertical motion of the Zhujiang Delta. Seismology & Geology, 23: 527-536 (in Chinese with English abstract).

De Deckker, P., 1981. Ostracods of athalassic saline lakes. Hydrobio-logia, 81: 131-144.

Dong, Y., Liu, C., Yin, J., Yang, X., Fürsich, F. T., Gao, F., 2007. Late Quaternary microfaunas and paleoenvironmental changes recorded in core sediments of the Pearl River Delta, South China. Vertebrata PalAsiatica, 45: 162-173.

Fang Guoxiang, Li Pingri, Huang Guangqing, 1991. Sea level chang-es in Zhujiang Delta during the past 8000 years. Geographical Research, 10: 1-11 (in Chinese with English abstract).

Feng Yingjun, 1983. Sea level changes and the lowest sea level since 40 000 yr B. P. in the East China Sea. The East China Sea, 1: 36-42 (in Chinese).

Frenzel, P., Boomer, I., 2005. The use of ostracods from marginal marine, brackish waters as bioindicators of modern and Quater-nary environmental change. Palaeogeography, Palaeoclimatol-ogy, Palaeoecology, 225: 68-92.

Gracia, F. J., RodríguezVidal, J., Cáceres, L. M., Belluomini, G., Be-navente, J., Alonso, C., 2008. Diapiric uplift of an MIS 3 marine deposit in SW Spain: Implications for Late Pleistocene sea level reconstruction and palaeogeography of the Strait of Gibraltar. Quaternary Science Reviews, 27: 2219-2231.


Hanebuth, T., Stattegger, K., Grootes, P. M., 2000. Rapid flooding of the Sunda shelf: a late-glacial sea-level record. Science, 288: 1033-1035.

Hanebuth, T. J. J., Saito, Y., Tanabe, S., Lan Vu, Q., Toan Ngo, Q., 2006. Sea levels during late marine isotope stage 3 (or older?) re-ported from the Red River Delta (northern Vietnam) and adjacent regions. Quaternary International, 145-146: 119-134.

He Zhigang, Mo Wenyuan, Liu Chunlian, Wu Chaoyu, 2007. Forma-tion of the Da’ao sand in the Pearl River Delta during the post-glacial period based on sedimentation rates and sediment grain size. Journal of Palaeogeography, 9: 331-336 (in Chinese with English abstract).

Hou Youtang, Chen Deiqiong, Yang Hengren, He Jundei, 1982. Cretaceous-Quaternary ostracod fauna from Jiangsu. Beijing: Geological Publishing House, 1-242 (in Chinese).

Hou Youtang, Gou Yunxian, Chen Deiqiong, 2002. Fossil Ostracoda of China. Beijing: Science Press, 1-1089 (in Chinese with Eng-lish abstract).

Huang, G., Yim, W. W. S., 1998. Holocene foraminiferal distribution in the Pearl River estuary and vicinity. In: Morton, B., (ed). The marine biology of the South China Sea. Hong Kong: The Hong Kong University Press, 331-341.

Huang Zhenguo, Li Pingri, Zhang Zhongying, 1982. Zhujiang (Pearl River) Delta. Guangzhou: Guangzhou Branch of Popular Science Press, 1-274 (in Chinese).

Huang Zhenguo, Zhang Weiqiang, Cai Fuxiang, Xu Qihao, 1995. On the lowest sea level during the culmination of the latest glacial period in South China. Acta Geographica Sinica, 50: 385-393 (in Chinese with English abstract).

Huang Zhenguo, Zhang Weiqiang, Chen Tegu, 1997. On the late Quaternary environment in Hong Kong area. Tropical Geogra-phy, 17: 157-163 (in Chinese with English abstract).

Huang Zhenguo, Cai Fuxiang, 2007. Buried weathering layers of the Late Quaternary and their environmental significance in the Zhujiang River estuary. Quaternary Researches, 27: 828-833 (in Chinese with English abstract).

Ingram, B. L., Ingle, J. C., Conrad, M. E., 1996. Stable isotope record of late Holocene salinity and river discharge in San Francisco Bay, California. Earth and Planetary Science Letters, 141: 237-247.

Ingram, C., 1998. Palaeoecology and geochemistry of shallow ma-rine Ostracoda from the Sand Hole Formation, Inner Silver Pit, southern North Sea. Quaternary Science Review, 17: 913-929.

Kienast, M., Hanebuth, T. J. J., Pelejero, C., Steinke, S., 2003. Syn-chroneity of meltwater pulse 1a and the Bølling warming: New evidence from the South China Sea. Geology, 31: 67-70.

Kim, J. M., Kennett, J. P., 1998. Paleoenvironmental changes as-sociated with the Holocene marine transgression, Yellow Sea (Hwanghae). Marine Micropaleontology, 34: 71-89.

Lan Xianhong, 1991. Sedimentary characteristics and strata division of core D22 of the Zhujiang (Pearl River) Delta. Oceanologia et Lim-nologia Sinica, 22: 148-154 (in Chinese with English abstract).

Lan Xianhong, 1996. Sedimentary characteristics of the Late Quater-nary in the Zhujiang (Pearl River) Delta. Acta Sedimentologica

Sinica, 14: 155-161 (in Chinese with English abstract).Lan, Xianhong, Ma Daoxiu, Xu Mingguang, Zhou Qingwei, Zhang

Guangwei, 1987. Some geochemical indicators of the Pearl River Delta and their facies significance. Marine Geology & Quater-nary Geology, 7: 39-49 (in Chinese with English abstract).

Li Congxian, Zhang Guijia, 1996. A primary study on high resolution sequence stratigraphy of Late Quaternary in the Yangtze river Delta area. Marine Geology & Quaternary Geology, 16: 15-22 (in Chinese with English abstract).

Li Guangzhao, Bian Yunhua, 1989. Foraminiferal distribution off Guangxi coastal area, Northern Bay. Acta Oceanologica Sinica, 11: 611-620 (in Chinese).

Li Pingri, Qiao Pengnian, Zheng Honghan, Fang Guoxiang, Huang Guangqing, 1991. The environmental evolution of the Zhujiang (Pearl River) Delta in the last 10000 years. Beijing: China Ocean Press, 1-154 (in Chinese with English abstract).

Li, P., Huang, G., Fang, G., Lin, X., 1994. Comparison of the Mid to Late Holocene environments between the South China coast and California, America. Chinese Science Bulletin, 39: 2081-2083.

Li Shuluan, 1985. Distribution of foraminifers in bottom sediments of the Pearl River estuary. Marine Geology & Quaternary Geol-ogy, 5: 83-104 (in Chinese).

Li Shuluan, 1994. A Preliminary Study of Foraminifera and Ostracod Assemblages in the Liaodong Bay. Acta Scientiarum Naturalium Universitatis Pekinensis, 30: 181-193 (in Chinese with English abstract).

Li Chunchu, 2004. Formation and evolution of estuaries of South China. Beijing: Science Press, 1-248 (in Chinese).

Liu Chunlian, Fürsich, F. T., Dong Yixin, Che Xiaoguang, Chen Liang, Zhuang, C., 2008. High resolution ostracod records of borehole PRD05 and the late Quaternary palaeoenvironment in Pearl River Delta. Journal of Palaeogeography, 10: 313-322 (in Chinese with English abstract)

Liu Chunlian, Wu Jie, Yang Tingting, Fürsich, F. T., Zhang Suqing, 2011. Rare earth element geochemistry of core sediments from the southern Pearl River Delta: its implications for geochemical response to paleoenvironmental changes during the Late Quater-nary. Journal of Palaeogeography, 13: 221-228 (in Chinese with English abstract).

Liu, S., 1997. Looking at high sea level of China Sea in the Late Pleistocene from remains of ancient sea level. Tropic Oceanol-ogy, 16: 23-31.

Liu Zhaoshu, Zhao Huanting, Fan Shiqing, Chen Sengqiang, 2002. Geology of the South China Sea. Beijing: Science Press, 1-502 (in Chinese).

Ma Daoxiu, Xu Mingguang, Zhou Qingwei, Zhang Guangwei, Lan Xianhong, 1988. Sedimentary facies of the Pearl River Delta. Marine Geology & Quaternary Geology, 8: 43-52 (in Chinese with English abstract).

Mazzini, I., Anadon, P., Barbieri, M., Castorinac, F., Ferreli, L., Gli-ozzi, E., Mola, M., Vittori, E., 1999. Late Quaternary sea level changes along the Tyrrhenian coast near Orbetello (Tuscany, cen-tral Italy): palaeoenvironmental reconstruction using ostracods.

361Vol. 2 No. 4


Marine Micropaleontology, 37: 289-311.Neale, J. W., 1988. Ostracods and palaeosalinity reconstruction. In:

De Deckker, P., Colin, J. P., Peypouquet, J. P., (eds). Ostracoda in the Earth Sciences. Amsterdam: Elsevier, 1-300.

Shi, Y., Yu, G., 2003., Warm humid climate and transgressions dur-ing 4030 ka B.P. and their potential mechanisms. Quaternary Sci-ences, 23: 1-11.

Ta, T. K. O., Nguyen, V. L., Tateishi, M., Kobayashi, I., Saito, Y., 2001. Sedimentary facies, diatom and foraminifer assemblages in a late Pleistocene-Holocene incised valley sequence from the Mekong River Delta, Bentre Province, Southern Vietnam: the BT2 core. Journal of Asian Earth Sciences, 20: 83-94.

Wang Pinxian, Zhang Jijun, Min Qiubao, 1980. Distribution of fo-raminifera in bottom sediments of the East China Sea. In: Wang Pinxian, (ed). Collected papers on marine micropaleontology. Beijing: China Ocean Press, 20-38 (in Chinese with English abstract).

Wang Pinxian, Zhang Jijun, Zhao Quanhong, Min Qiubao, Bian Yunhua, Zheng Lianfu, Chen Ronghua, 1988. Foraminifera and Ostracoda in bottom sediments of the East China Sea. Beijing: China Ocean Press, 1-438 (in Chinese with English abstract).

Wang Qiang, Zhang Yufa, Yuan Guibang, Zhang Wenqing, 2008. Since MIS 3 stage the correlation between transgression and cli-matic changes in the north Huanghua area, Hebei. Quaternary Sciences, 28: 79-95 (in Chinese with English abstract).

Wang Zhigen, 1998. Foraminifers from the Quaternary Kengkou Formation in Liyumen, Hongkong. In: Li Zuoming, Chen Jinhua, He Guoxiong, (eds). Research on palaeontology and stratigraphy in Hongkong. Beijing: Science Press, 92-127 (in Chinese).

Wang Zhanghua, Zhao Baocheng, Chen Jing, Li Xiao, 2008. Chron-ostratigraphy and two transgressions during the Late Quaternary in Changjiang delta area. Journal of Palaeogeography, 10: 99-110 (in Chinese with English abstract).

Wei, X., Wu, C. Y., 2011. Holocene delta evolution and sequence stratigraphy of the Pearl River Delta in South China. Science China, Earth Sciences, 54: 1523-1541.

Wen Xiaosheng, Zhao Huanting, Zhang Qiaomin, Song Chaojing, 1997. Depositional characteristics and environmental evolution in Lingding Yang cores. Acta Oceanologica Sinica, 19: 122-127, 129 (in Chinese).

Wu, C., Ren, J., Bao, Y., Shi, H., Lei, Y., He, Z., Tang, Z., 2006. A preliminary study on the morphodynamic evolution of the ‘Gate’ of the Pearl River Delta, China. Acta Geographica Sinica, 61: 537-548.

Wu, C., Zhou, D., 2001. Long term morphodynamics in a special type of estuary. Science in China (Series B), 44: 112-125.

Xu Mingguang, Ma Daoxiu, Zhou Qingwei, Zhang Guangwei, Lan Xianhong, 1986. Quaternary sea level fluctuation in Zhujiang River Delta area. Marine Geology & Quaternary Geology, 6: 93-102 (in Chinese with English abstract).

Yang Dayuan, Chen Kefeng, Shu Xiaoming, 2004. A preliminary study on the paleoenvironment during MIS 3 in the Changjiang Delta region. Quaternary Sciences, 24: 525-530 (in Chinese

with English abstract).Yim, W. W. S., He, X. X., 1991. Distribution of foraminifera in Late

Quaternary sediments off High Island, Hong Kong. Journal of Southeast Asian Earth Sciences, 6: 1-11.

Yim, W. W. S., Ivanovich, M., Yu, K. F., 1990., Young age bias of radiocarbon dates in preHolocene marine deposits of Hong Kong and implications for Pleistocene stratigraphy. GeoMarine Let-ters, 10: 165-172.

Yim, W. W. S., 1999., Radiocarbon dating and the reconstruction of late Quaternary sea level changes. Quaternary International, 55: 77-91.

Yokoyama, Y., Kido, Y., Tada, R., Minami, I., Finkel, R. C., Matsu-zaki, H., 2007. Japan Sea oxygen isotope stratigraphy and global sea level changes for the last 50,000 years recorded in sediment cores from the Oki Ridge. Palaeogeography, Palaeoclimatology, Palaeoecology, 247: 5-17.

Yu Zhenjiang, Guo Shengqiao, Liang Xiaohong, Zhang Yuping, Wang Ruhua, 2005. Transgression layers in the Yangtze Delta area (southern Yangtze). Journal of Stratigraphy, 29: 618-625 (in Chinese with English abstract).

Zhao, H., Chen, M., Yu, J., Yuan, J., 1987. A preliminary study on the micropaleontology of transgressive layers in Zhujiang (Pearl River) Delta. Tropic Oceanology, 16: 28-36.

Zhao Quanhong, 1987. A study of the distribution of Recent ostracod faunas from coastal areas of the East China and Yellow Seas. Acta Oceanologica Sinica, 6: 413-420 (in Chinese).

Zhao Quanhong, 1980. Discovery of a Late Quaternary brackish wa-ter fauna in the region west of the Weishanhu Lake, Jiangsu Prov-ince, and its significance. In: Wang Pinxian, (ed). Collected pa-pers on marine micropaleontology. Beijing: China Ocean Press, 120-129 (in Chinese with English abstract).

Zhao Quanhong, Wang Pinxian, Zhang Qinglan, 1986. Distribution of ostracods in bottom sediments of the northern shelf area of the South China Sea. Acta Oceanologica Sinica, 8: 590-602 (in Chinese).

Zhao Quanhong, Wang Pinxian, 1988. Modern Ostracoda in sedi-ments of shelf seas off China:quantitative and qualitative dis-tributions. Oceanologia et Limnologia Sinica, 19: 553-561 (in Chinese with English abstract).

ZhaoZhao Quanhong, Wang Pinxian, 1990. Modern Ostracoda in shelf seas off China: Zoogeographical zonation. Oceanologia et Limno-logia Sinica, 21: 458-464 (in Chinese with English abstract).

Zhu Xiaodong, Shi Bingwen, You Kunyan, Zhu Dakui, 1998. Fo-raminiferal taphocoenose in Haizhou Bay, Jiangsu (China) and its relationship to sedimentary environment. Scientia Geographi-ca Sinica, 18: 147-155 (in Chinese with English abstract).

Zong, Y., 2004. Mid-Holocene sealevel highstand along the south-east coast of China. Quaternary International, 117: 55-67.

Zong, Y., Yim, W. W. S., Yu, F., Huang, G., 2009. Late Quaternary environmental changes in the Pearl River mouth region, China. Quaternary International, 206: 35-45.

(Edited by Wang Yuan, Liu Min)

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Late Quaternary palaeoenvironmental changes documented …Late Quaternary palaeoenvironmental changes ... tant representatives in estuarine environments due to their wide ecological