East coastal area of Fujian province, centring on the Funing bay, is a major concentrated area of Neolithic culture sites in the middle and lower reaches of Min River which is the longest river in Fujian province of China, with largest water and most extensive area. A large number of neolithic remains were found around this area. Those sites are the firsthand evidence for long-term use of marine resources and coastal environments in human evolution and subsequent development which is vital to understanding patterns of human subsistence (Nian,
discovered and excavated in Xiapu county, east coastal area of Fujian (Fujian provincial museum, 2017). Of particular significance is the Huangguashan Neolithic culture (4300–3500 cal BP) (Lin, 2012; Fan
The modern topographic features of the research area are mainly showed by coastal plains, ocean bays and winding shorelines. And the palaeoenvironment changes of regions to the north and south of Fujian show a remarkable difference since the early Holocene which can influence the transformation of Neolithic archaeological sites in this area (e.g. Zong , 2004; Ma
This study aims to fill the gap in our knowledge of the coupling relationship between regional environmental change and Neolithic cultural response of South China. The study in German North Sea coast of Zhang
The Funing bay is a silty coast and located in Xiapu County, the east coastal area of Fujian province in southern China about 2 km far away from East China Sea rim (
Map showing the sampling location and the terrain features of research area. The yellow squares represent the typical sites of North Fujian.
Sampling location, altitude and lengths of the Funing bay sediment cores and Neolithic sites.
Core number or site | Sampling location | Latitude N | Longitude E | Altitude (m) Altitude | (m) error Core | (length m) |
---|---|---|---|---|---|---|
FN1 | Muddy tidal flats near supratidal zone of Funing bay | 26°48'52.57" | 120°01'19.49" | 15 | 3 | 15 |
FN2 | Foot of Pingfeng hill | 26°48'44.26" | 120°00'00.80" | 26 | 3 | 3.4 |
Pingfengshan site | Hilltop of Pingfeng hill | 26°48'36.63" | 119°59'44.40" | 163 | 3 | —— |
Huangguashan site | Hilltop of Huangguashan hill | 26°47'50.22" | 119°55'24.74" | 50 | 3 | —— |
Optically stimulated luminescence (OSL) dating of quartz has been used successfully and revolutionized since the early 2000s, and this technique can be applied to estimate depositional age of the sediments in different sedimentary environments (Aitken, 1998; Wintle and Murray, 2006). The core chronologies are based on 17 quartz-OSL age data of the sediments.
All sample preparation was conducted under subdued red light. The middle part of sediment in each tube was pretreated with 10% HCl to remove carbonates and with H2O2 to remove the organic matter. The 38–63 μm fractions were etched with 40% HF for 40 minutes to dissolve feldspars and subsequently treated with 10% HCl to remove acid-soluble fluoride precipitates. The purity of the extracted quartz grains were checked using IR stimulation. The single aliquot regenerative dose (SAR) protocol (Murray and Wintle, 2000) was applied to purified medium-grained quartz (38–63 μm) OSL measurement.
Samples were dated by OSL laboratory of Fujian Normal University. OSL measurements were undertaken using an automated RisØ-TL/OSL DA-20C/D reader with 7.5 mm Hoya U-340 filters (290–370 nm) in front of an EMI 9235 QA photomultiplier tube. Irradiation was provided by a 90Sr/90Y beta source (Bøtter-Jensen
In order to understand the grain-size distribution of the sediment, the sediment samples at intervals of 10 cm were analyzed by a Malvern Mastersizer 2000 laser particle size analyzer. 30% hydrogen perocide (H2O2) and 10% dilute hydrochloric acid (HCl) were used to remove organic material and carbonates. And the samples were dissolved in 0.05 mol/L sodium hexametaphosphate ((NaPO3)6) solution to disperse the samples, then the solutions were measured after ultrasonic desaggregation for 10 s on the machine.
The FN1 core consists of silt and sandy material. As a whole, the core can be divided into three different stratigraphic stages (
Lithology and grain-size characteristics of FN1 core at Funing bay, Southeast China. And FN1 and FN2 core are located in intertidal zone and supratidal zone, respectively. (a) The distribution of median diameter with depth. The solid circles on FN1 lithology column represent the sampling location of OSL samples. (b) The distributions of different cumulative percentage composition with depth. (c) The sorting coefficient of sediment.
The boundary between the clay silt of the uppermost unit A and the second unit B is visible at the depth of ~700 cm. Sediment composition changes abruptly and a significant step has developed in the unit B (
The boundary to the lowest unit C of the FN1 core is sharp and occurs at depth of ~1270 cm (
The bed rock of granite was found about 1450 cm below the unit C at the bottom of FN1 core.
The results from grain-size analyses show that the sorting coefficient of unit A and C are good-mid sorting, and the value of unit B is poor-mid sorting (
Luminescence characteristics. (a) and (b). Solid squares display equivalent dose as a function of preheat temperature for the medium grained quartz for the sample PFS005 and PFS012, respectively. Open squares and circles refer to the recycling ratios and recuperation values. (c). Dose recovery test data for sample PFS005 and PFS012.
Based on the results of preheat plateau test and dose recovery test, a preheat at 220°C (10 s) and a cut heat at 180°C (10 s) were used for samples (PFS001-PFS008, PFS015), and a preheat at 240°C (10 s) and a cut heat at 200°C (10 s) were selected for the rest of samples (PFS009-PFS014). Then samples were stimulated by blue light at 130°C for 40s. The first 1.6s of the initial OSL signal minus a background estimated from the last 16s OSL signal was used as a measurement of the last component for
Luminescence characteristics. Typical natural OSL decay curves (a–c) using the SAR procedure for mid-grained quartz of sample PFS001, PFS002 and PFS005. The OSL dose response curves (d–f) are plotted from all aliquots of each sample. Radial plots showing how broad the distribution of the De values of sample PFS001 (g), PFS002 (h), and PFS005 (i). The resultant De value of the central age model (Table 2) is shaded.
The OSL data of FN1 and FN2 cores at Funing bay, Southeast China.
Sample ID In lab | Sample ID | K (%) | Th (ppm) | U (ppm) | Water content (%) | Cosmic dose rate (μGy/ka) | Dose Rate (Gy/ka) | Age (ka) | |
---|---|---|---|---|---|---|---|---|---|
FNU2016027 | PFS001 | 2.58 ± 0.07 | 33.6 ± 0.81 | 8.63 ± 0.21 | 10 ± 3 | 0.179 ± 0.022 | 6.48 ± 0.29 | 5.52 ± 0.10 | 0.845 ± 0.041 |
FNU2016028 | PFS002 | 2.58 ± 0.07 | 30.9 ± 0.74 | 10.3 ± 0.24 | 10 ± 3 | 0.151 ± 0.012 | 6.65 ± 0.30 | 5.20 ± 0.07 | 0.776 ± 0.037 |
FNU2016030 | PFS003 | 2.94 ± 0.07 | 27.6 ± 0.66 | 7.72 ± 0.20 | 10 ± 3 | 0.134 ± 0.010 | 6.28 ± 0.56 | 5.96 ± 0.08 | 0.960 ± 0.047 |
FNU2016029 | PFS004 | 3.65 ± 0.08 | 13.1 ± 0.35 | 2.84 ± 0.10 | 10 ± 3 | 0.121 ± 0.023 | 4.81 ± 0.26 | 9.79 ± 0.12 | 2.019 ± 0.111 |
FNU2016031 | PFS005 | 3.30 ± 0.08 | 18.7 ± 0.49 | 6.04 ± 0.16 | 10 ± 3 | 0.107 ± 0.016 | 5.64 ± 0.31 | 25.70 ± 0.48 | 4.610 ± 0.243 |
FNU2016032 | PFS006 | 3.42 ± 0.08 | 19.8 ± 0.51 | 5.92 ± 0.16 | 10 ± 3 | 0.086 ± 0.006 | 5.78 ± 0.28 | 27.15 ± 1.18 | 4.760 ± 0.314 |
FNU2016033 | PFS007 | 3.56 ± 0.08 | 17.8 ± 0.46 | 4.81 ± 0.14 | 10 ± 3 | 0.070 ± 0.005 | 5.51 ± 0.28 | 34.78 ± 0.80 | 6.393 ± 0.358 |
FNU2016034 | PFS008 | 3.31 ± 0.08 | 18.6 ± 0.48 | 5.02 ± 0.15 | 10 ± 3 | 0.064 ± 0.005 | 5.38 ± 0.27 | 67.24 ± 0.27 | 12.666 ± 0.69 |
FNU2016035 | PFS009 | 3.25 ± 0.07 | 23.9 ± 0.60 | 6.50 ± 0.23 | 10 ± 3 | 0.054 ± 0.004 | 5.98 ± 0.29 | 162.35 ± 4.92 | 27.466 ± 1.58 |
FNU2016036 | PFS010 | 3.56 ± 0.08 | 15.4 ± 0.40 | 4.07 ± 0.13 | 10 ± 3 | 0.049 ± 0.004 | 5.16 ± 0.27 | 144.18 ± 10.15 | 28.259 ± 2.48 |
FNU2016037 | PFS011 | 3.86 ± 0.08 | 21.20 ± 0.53 | 6.480 ± 0.17 | 10 ± 3 | 0.044 ± 0.004 | 6.27 ± 0.31 | 140.05 ± 4.07 | 22.345 ± 1.29 |
FNU2016038 | PFS012 | 2.77 ± 0.07 | 26.00 ± 0.62 | 7.910 ± 0.20 | 10 ± 3 | 0.035 ± 0.002 | 5.91 ± 0.28 | 324.17 ± 28.66 | 54.854 ± 5.50 |
FNU2016039 | PFS013 | 3.38 ± 0.08 | 25.90 ± 0.62 | 8.320 ± 0.20 | 10 ± 3 | 0.032 ± 0.003 | 6.53 ± 0.31 | 271.92 ± 16.75 | 41.617 ± 3.25 |
FNU2016040 | PFS014 | 3.73 ± 0.08 | 24.30 ± 0.61 | 5.850 ± 0.16 | 10 ± 3 | 0.031 ± 0.002 | 6.20 ± 0.31 | 309.22 ± 18.04 | 49.892 ± 3.83 |
FNU2016041 | PFS015 | 3.57 ± 0.08 | 23.00 ± 0.58 | 5.570 ± 0.16 | 10 ± 3 | 0.176 ± 0.148 | 6.06 ± 0.33 | 45.60 ± 1.260 | 7.530 ± 0.46 |
As what mentioned before, the laboratory parameters such as preheat, recycling ratios and recuperation of medium-quartz indicate that those OSL signals are fit for
Ages comparison.
AMS 14C and OSL dating results from Pingfengshan site.
Site | Laboratory code | Context NO. | Sample type | Calibrated (2σ range) date | Reference |
---|---|---|---|---|---|
Pingfengshan | Beta-434875 | Layer 3 | charcoal | 3565–3403 cal. BP | Fujian Provincial Museum, 2017 |
Beta-434876 | Layer 4 | charcoal | 3691–3495 cal. BP | ||
Beta-434877 | Layer 5 | charcoal | 3582–3450 cal. BP | ||
Beta-434878 | Layer 5 | charcoal | 3716–3572 cal. BP | ||
UGAMS#27094 | Layer 3 | rice | 3692–3570 cal. BP | Deng |
|
UGAMS#27093 | Layer 4 | rice | 3684–3494 cal. BP | ||
UGAMS#27092 | Layer 5 | rice | 3826–3632 cal. BP | ||
FNU2016003 | Layer 4 | quartz | 3.38 ± 0.37 ka | This study | |
FNU2016004 | Layer 5 | quartz | 4.00 ± 0.19 ka | ||
FNU2016008 | Layer 4 | quartz | 3.38 ± 0.16 ka | ||
FNU2016009 | Layer 4 | quartz | 3.30 ± 0.16 ka |
The ages and grain-size results identify three distinct environmental units in the transformation of the Funing bay and the coastal area of north Fujian (
The chronology of FN1 core and compared with fluctuation of sea level. The dash lines in 6a and 6b represent the global sea level change (Lambeck et al., 2002) and the sea level change of North Fujian (Zeng, 1991), respectively. The red cycle in 6b represents the age of corn FN2.
Sketch map of shoreline change of northeast coastal area of Fujian province, China at different stages.
The earliest stage is roughly corresponding to marine oxygen isotope (MIS) stage 3. The duration of the unit C formation is approximately equal to 60–40 ka from now based on laboratory test results. The mean relative sea level of MIS 3 was about –55 m above sea level (a.s.l) (Kenneth
The deposition process of the second stage mainly occured in the MIS3/2 transition and MIS 2. It is mainly continental deposit (in particular, fluvial alluvial and proluvial facies, a small part of aeolian sand deposit) based on the chromaticity and granularity of FN1 core (unit B). This sedimentary facies occur in response to the rapid falling of sea level following the relative thalassocratic period of MIS 3. In some tectonically stable areas or neighbouring regions where the tectonic rate is known and has been removed from the observed signal, a similar phenomenon can be observed (Wang
The uppermost 700 cm of sediments (unit A), which are mainly corresponding to mid-late Holocene (MIS 1), represents the final stage in the evolution of the FN1 core depositional environment. The transition to unit A is characterized by steep increase in fine grained content and a steep decline in coarse grained content, coupled with a good-mid sorting and light grey colour. Seven OSL data are 6.393 ± 0.358 ka, 4.76 ± 0.314 ka, 4.61 ± 0.243 ka, 2.019 ± 0.111 ka, 0.960 ± 0.047 ka, 0.776 ± 0.037 ka and 0.845 ± 0.041 ka, respectively. The clay and silt deposit represent a neritic environment, which conform to the result of high sea-level in this period. It has been proved that three thalassocratic stages have raced at coastal area of Fujian since about 7 ka, and the highest sea level was usually less than 4 m a.s.l compared with nowadays (Wang
As noted above, there is still significant uncertainty over the timing, magnitude and variability of the Holocene highstand in coastal area of Fujian (the west coast of the Taiwan Straits) (Wang
The deposit of unit A (FN1 core) represents the Holocene sea level history. Of particular interest is the clayey silt deposit near the base of unit A stratigraphic sequence (~6.7 m below surface). This layer dated about 6.4 ka likely accumulated along the shoreline during the marine transgression, which corresponds to a large scale transgressive event deposition named “Changle transgression” by Lin (1979). Thus, this result marks the intertidal zone during the Mid Holocene “Changle transgression” of Funing bay. A simple estimation of relative sea level for this index layer, using the present elevation above sea level minus the depth and the tidal data, suggests that it was 2.78 m. It provides a useful approximation for contrast with sea level change from other studies. This estimate of 2.78 m at 6.4 ka is roughly consistent with data form Zeng (1991), which measures relative sea level at 6.1 ka at 3 m. So the lower deposits of unit A provides another sea level indicator.
A transition period between the yellow medium sand layer at 2–2.5 m and the light grey fine sand layer at 2.5–7 m provides an obvious transgression-regression cycle dated to 0.96 ka (~2.2 m) and 2.0 ka(~2.9 m), respectively. Funing bay used to be a ship-building base of the ancient Wenma County which is part of kingdom of Wu in the Period of Three Kingdoms (220–280 AD). A boat was discovered in the foot of Pingfengshan hill and dated 75 to 235 AD under 2 sigma calibration based on AMS radiocarbon dating (Fujian provincial museum, 2017). It can provide evidence that there was a period of sea level rising. That is, there was enough water to float the boat as an ancient port. The discard of ship-building base was very likely related to the change of sea level of the time.
Why there were no sites older than 4.3 ka cal BP discovered in research area so far? It is extremely likely that sea-level fluctuations played an important role in human activities and migrations since about 7 ka (Chen
Of flourish ancient culture of research area is Huangguashan culture (age range is about 4.3–3.5 ka cal BP). This period characterized by low intensity agriculture and agricultural activities might be the supplement of maritime economy base on the analysis of excavated datum (Fujian provincial museum, 2017). As far as time alignment is concerned, the lifespan of Pingfengshan site (3.8–3.5 ka cal BP) is later than that of Huanggaushan site (4.3–3.8 ka cal BP). This appearance precisely corresponds to the process of sea level rising from 4.3 ka to 3.5 ka (
Numerous studies have now shown that there was a period of higher sea level at about 2.0–1.5 ka before present (Zeng, 1997; Lin, 2012; Ma
The human-environment interactions in coastal area of South China are still controversial because of the scarcity of a reliable and systematic chronology of both deposit sediments and archaeological sites. In this study, we presented the OSL ages obtained from the medium-grained quartz of FN1 core and Pingfengshan site at the Funing bay along the coastal of Fujian province, China. SAR measurements of archaeological site (Pingfengshan site) yielded internally and stratigraphically consistent ages within errors, indicating competent reliability of the technique verified with AMS 14C technique. The results showed that the ages of FN1 core deposit were varied from 50 ± 4 ka to 0.8 ± 0.04 ka. The deposit periods linked to MIS 3c/b, MIS 3/2 and MIS 1, respectively. And there is a visible break between MIS 2 and MIS 1. The core has a continuous sediment record from around 7 ka until the present. This time period spans the entire Neolithic era of the Fujian archaeological sequence. Based on the direct correspondence between sea level change and different Neolitic culture periods, we deduce that the cultural types of Keqiutou culture and Huangguashan culture all belong to coastal mountainous culture, of which flourishing periods corresponds to the higher sea level periods of mid-late Holocene. Tanshishan culture belongs to estuarine coastal culture, and most sites of this period correspond to a lower sea level period located at lower altitudes. However, at present we could not establish a precise correspondence between sea level change and human dispersal, due to the scarcity of chronology. More dating work is required, and accurate chronologies for Neolithic sites and coastal deposit cores will be the research focus in our further work.
Besides, what deserve attention especially is that the sample pretreatment and grain size component are important for us to make a correct assessment of the grain size of grains being measured and the corresponding dose rate component (Armitage and Bailey, 2005). And the water contents are also important for calculating the dose rates. Paying more attention to those influence factors is required in future work.