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... Recently, increasing research attention has been devoted to the Quaternary geology of Liaodong Bay, and a great number of references have been published (Li et al., 2019；Wang et al., 2008；Lan et al., 2016c；Sun et al., 2015；Wu et al., 2005；Wang et al., 2008Zhang et al., 2014). Compared to the researches in the west coast of Bohai Bay (Yan et al., 2006；Xu et al., 2011；Xiao et al., 2014；Li and Wang, 2014；Xu et al., 2018；Hu et al., 2014；Wang and Li, 1983Shi et al., 2009), such as Laizhou Bay and its coastal areas, and the Yellow River Delta (Yi et al., 2012；Jiang et al., 2016Liu et al., 2016;Zhuang et al., 1999), the Liaodong Bay is the area lacking deep boreholes and precise chronological dating. Reconstruction of the burial depth and distribution characteristics of the strata in different periods in the area still requires many Accumulation of deep hole research. ...
... The Borehole JXC-1 is located in the northeast of the mud area of Bohai Sea, within a relatively stable depositional environment (Qiao et al., 2010a,b;Liu et al., 2007). Existing research results indicate that the Bohai Sea and surrounding areas have relatively continuous sedimentation since Neogene (Yao et al., 2006;Xiao et al., 2008Xiao et al., , 2014Yi et al., 2015;Shi et al., 2009). Except for paleo-uplift areas, there is no large unconformity occurred. ...
The environmental evolution and provenance of the sediments since 1.2 Ma penetrated by the borehole of JXC-1 in Northwestern Liaodong Bay are studied in this paper using the data from accelerator mass spectrometry ¹⁴C dating, optically-stimulated luminescence dating, paleomagnetic dating, qualitative and quantitative analysis of benthic foraminifera, and the geochemistry analysis. Based on regional stratigraphic correlation, the evolution of sedimentary environment and provenance are discussed. The study suggests that large-scale transgression began by the end of Middle Pleistocene, and invaded into this region for three times from Late Middle Pleistocene to Holocene, in MIS 7, MIS5, and MIS1, that is in consistent with the global pattern of sea level changes. The results of this study are different from previous researches in the Bohai Sea, which found three times of transgressions in MIS5, MIS3, and MIS1 respectively. There are two possibilities, either no transgression in the Bohai Sea, or the transgression did not enter Liaodong Bay during the time of MIS3. Provenance analysis shows that the northwest of Liaodong Bay is a mixed depositional area. Sediments are mainly sourced from the Yellow River, Liaohe River (formerly Shuangtaizi River) and Daliao River. During the three marine phases, the sediments of the JXC-1 borehole came mainly from the Yellow River characterized by high content of CaO, and deposited under the control of Bohai Sea circulation and coastal currents. The sediments in depths of 36.00–46.00 m and 58.20–70.30 m of the borehole are high water level lacustrine sediments, mainly came from the Yellow River. However, the sediments in depths of 46.00–58.20 m are mainly brought in by the Liaohe and Daliao rivers. All these studies suggest that the sediments coming from the Yellow River may be distributed northward up to 40.5°N. As a major conclusion different from previous understandings, this paper provides an important reference for the evolution of the sedimentary environment and the provenance of the Late Quaternary deposits of the Bohai Sea.
... There is disagreement, however, concerning the timing of the earliest marine transgression and the Quaternary sedimentary history of the region as inferred from these cores. For instance, the initial transgression has been reported to have occurred in the Early Pleistocene around 2300 kyr BP (Wang et al., 1987), in the Middle Pleistocene between 417 and 460 kyr BP (Zhuang et al., 1999), at about 500 kyr BP (Shi et al., 2009), or at 260 kyr BP (Yi et al., 2015) ; similarly, the environment of the western Bohai Sea region has been reported to have been mainly fluvial from ~3.3 to ~0.10 Ma (Yao et al., 2012 ) or to have been occupied by the Bohai Paleolakes before 260 ka BP (Yi et al., 2015). Studies of shorter cores containing sediments deposited during the Late Pleistocene and Holocene have reported the existence of three marine sedimentary beds around the Bohai Sea, deposited during the Holocene and in Marine Isotope Stage (MIS) 3 and MIS 5 (e.g., Wang and Tian, 1999; Yan et al., 2006a; Liu et al., 2009). ...
... Chen et al. (2012) also suggested on the basis of OSL dating that the marine sediments corresponding to the third bed, formerly interpreted to have been deposited in MIS 5, were deposited in MIS 7. Similarly, radiocarbon ages of pre-Holocene sediments in other parts of the world (e.g., Simms et al., 2009; Madsen et al., 2008 ) have been shown to be underestimations due to a young age bias caused by contamination of the sediments with young carbon (Yim et al., 1990; Pigati et al., 2007). Among cores that have been collected from the Bohai Sea region, sediments deposited during various parts of the Neogene and Quaternary show great spatial differences in thickness (e.g., Yan et al., 2006b; Xiao et al., 2008; Shi et al., 2009; Yao et al., 2012) , which have been ascribed to the complex neotectonic structure of the Bohai Basin (e.g., Wang and Tian, 1999; Yan et al., 2006b; Tang et al., 2008 ). The considerable differences in sediment thickness make it difficult to make stratigraphic comparisons and thus to correlate marine sediments among the cores, which complicates age assessment of Quaternary transgressive events. ...
... There is disagreement, however, concerning the timing of the earliest marine transgression and the Quaternary sedimentary history of the region as inferred from these cores. For instance, the initial transgression has been reported to have occurred in the Early Pleistocene around 2300 kyr BP (Wang et al., 1987), in the Middle Pleistocene between 417 and 460 kyr BP (Zhuang et al., 1999), at about 500 kyr BP (Shi et al., 2009), or at 260 kyr BP (Yi et al., 2015); similarly, the environment of the western Bohai Sea region has been reported to have been mainly fluvial from~3.3 to~0.10 ...
... Among cores that have been collected from the Bohai Sea region, sediments deposited during various parts of the Neogene and Quaternary show great spatial differences in thickness (e.g., Yan et al., 2006b;Xiao et al., 2008;Shi et al., 2009;Yao et al., 2012), which have been ascribed to the complex neotectonic structure of the Bohai Basin (e.g., Wang and Tian, 1999;Yan et al., 2006b;Tang et al., 2008). The considerable differences in sediment thickness make it difficult to make stratigraphic comparisons and thus to correlate marine sediments among the cores, which complicates age assessment of Quaternary transgressive events. ...
Because the Bohai Sea is a semi-enclosed sea connected to the North Yellow Sea only via the Bohai Strait, its sedimentary evolution during the Quaternary has been complex. In particular, the timing of Quaternary transgressions, especially Pleistocene transgressions, in the region, has long been a matter of controversy. Thus, the sedimentary history of the Bohai Sea in the Quaternary is still poorly understood. Borehole core YRD-1101 (200.30 m long), drilled in 2011 on the northern coast of the modern Yellow River delta, covers the last ~ 1.90 Ma, as indicated by paleomagnetic measurements. Here we report the results of integrated analyses of the core, including its sedimentary characteristics, downcore changes in environmental proxies (benthic foraminifers and ostracods), and accelerator mass spectrometry (AMS) 14C and optically stimulated luminescence (OSL) dates. From ~ 1.9 to ~ 0.83 Ma, the environment was fluvial. The first Quaternary transgression occurred at ~ 0.83 Ma (the latest Early Pleistocene), presumably caused by minor subsidence of the Miaodao Islands Uplift. Several relatively weak transgressions occurred from ~ 0.83 Ma to the end of the Middle Pleistocene, and three major marine sedimentary beds, here called T-3, T-2, and T-1 in ascending order, recorded in the early to middle MIS 5, the early MIS 3, and the middle to late Holocene, respectively, were presumably caused by major subsidence of the Miaodao Islands Uplift. In transgression strength, T-3 was weaker than T-2, which was basically the same as T-1. We interpret the change in transgression strength to reflect the interplay of sea-level changes, neotectonic subsidence, and sediment supply changes. Comparisons with other cores from around the Bohai Sea showed that the thickness of the Quaternary sedimentary sequence differs significantly among them, and both the T-2 and T-3 clearly display differences in thickness, facies sequence, and completeness among the cores, highlighting the important role of tectonic activity in the evolution of the Quaternary stratigraphy in the Bohai Bay Basin.
... The latest transgression occurred in Holocene, about 9 ka BP and the Late Pleistocene transgression is about 34-32 ka BP. The third transgression happened in the early of the Late Pleistocene, about 110-70 ka BP and the two transgressions of Middle Pleistocene, occurred around 150 and 300 ka BP, respectively (Shi et al., 2009;Wang, 2006). Figure 2 shows the lithology of G1 and G2 boreholes with the depth of 500 m that we studied, although the total depth of G2 is 1 226 m. ...
... c (220-150 m), late of the Early Pleistocene sediments, δ 18 O values showed a slightly negative change, indicating a colder climate. d (150-0 m), Middle and Late Pleistocene sediments, in this area, climatic fluctuations frequently occurred since the Middle Pleistocene, along with several transgressions (Wang et al., 2008;Shi et al., 2009). δ 18 O values of pore water were impacted by interact deposition of terrestrial and marine sediments, showing significant signature in different sediments facies. ...
The record of paleo-environment in clayey aquitard pore water is much more effective relative to aquifer groundwater owing to the low permeability of clayey aquitard. Oxygen-18 (18O), deuterium (D), and chemical patterns were determined in pore water samples extracted from two 500 m depth boreholes, G1 and G2, in western Bohai Bay, China. Shallow pore water samples (depth<102 m) are saline water, with the TDS (total dissolved solids) of 3.69–30.75 g/L, and deeper ones (depth=102–500 m) are fresh water, with the TDS<1 g/L. Content of major ions (i.e., Cl-, Na+, K+, Mg2+, SO4
2-, Ca2+) is high in marine sediment pore water samples and gradually decrease towards to terrestrial sediment pore waters, together with the Cl/Br and Sr/Ba ratios changing significantly in different sedimentary facies along the study profile, indicating that pore water may be paleo-sedimentary water and not replaced by modern water. δ18O profile and positive correlation between δ18O and Cl- of shallow saline pore water indicated diffusion as the main transport mechanism, and distinguished four transgressive layers since Late Quaternary (i.e., Holocene marine unit, two Late Pleistocene marine units and Middle Pleistocene marine unit), further supporting the finding that pore water retained the feature of paleo-sedimentary water. Climate was identified as the main influence on the isotopic signature of aquitard pore waters and four climate periods were determined by δ18O profile.
... Some previous studies reported a moderately high SAR continuously from the early to middle Pleistocene, and the Matuyama-Brunhes (M-B) boundary was probably buried deeper than 100 m (e.g., IOCAS, 1985;Zhao, 1995). However, more recent studies stated that the M-B boundary should be shallower and that a relatively slow SAR or significant depositional hiatus occurred during this period (e.g., Shi et al., 2009). Our results confirm that the SAR descended from a moderately high level (17 cm/ka) to a low level (4.3 cm/ka), but no major depositional hiatus has occurred since the early Pleistocene in the study area. ...
... This is also the reason why the sedimentology of upper Quaternary marine deposits around the marginal seas of China is comparable (e.g., Zhao et al., 1978;Zhao, 1995;Wang and Tian, 1999;Li et al., 2008;Liu, 2009;Yi et al., 2012a), but their relative ages are still hotly debated. Specifically, the beginning of marine deposition was determined to be during marine isotope stage (MIS) 5 (130-71 ka) (e.g., IOCAS, 1985;Zhao, 1995;Wang and Tian, 1999;Zhuang et al., 1999), but MIS 7 (243-191 ka) or older based on luminescence or uranium-series dating (e.g., Yim et al., 1990;Chen et al., 2008;Yi et al., 2012aYi et al., , 2013, or magnetostratigraphy (e.g., Yao et al., 2006;Shi et al., 2009). However, all previous studies only relied on one method of age extrapolation and no report provided absolute age constraints or cross-calibration of several independent geochronologies. ...
... Unlike previous studies, they concluded that the marine transgression did not impact the studied area during the MIS3. Recently, information gathered from boreholes BZ1, BZ2, and CQJ4, all of which were drilled in the west coast of the Bohai Bay ( Fig. 1), also significantly pushed back the age of the three transgression, as indicated by the magnetostratigraphy method (Yao et al., 2006;Xiao et al., 2008;Shi et al., 2009) and lumines-cence (Chen, Li et al., 2008). If the proposal made by Chappell et al. (1996) is correct-that is, if the global sea level was 60-80 m lower than at present during 30-70 ka-then how the MIS3 transgression occurred in the Bohai Sea is questionable. ...
... However, based on foraminifera assemblages and dating information of Lz908, together with comparisons with the Shouguang E core (Zhao, 1995;Yao et al., 2010; Fig. 1), three major transgressive events could be related to the four marine/coastal sedimentary units, and their ages were related to MIS7, MIS6, MIS5-3 and the Holocene period, respectively. The timing of transgressions support previous along the Chinese marginal seas (e.g., Yim et al., 1990;Chen et al., 2012, Yao et al., 2006, Xiao et al., 2008, Shi et al., 2009), but these data differ significantly from work described by Han and his colleagues (Han et al., 1994), Zhao's group (Zhao, 1995) and Zhang's laboratory (Zhang et al., 1996). ...
Controlled by climate changes, there were three large-scale transgressions and regressions around the Bohai Sea during the late Quaternary, which were accepted by most geologists. However, a big controversy still exists about the time when the transgressions occurred separately. In order to find out the process of the paleoenvironmental changes around the Bohai Sea in the late Quaternary, the foraminifera assemblages from a new borehole Lz908 in the southern coast of the Laizhou Bay were studied, and then the transgressive strata were indentified. Combined with accelerator mass spectrometry radiocarbon 14C (AMS14C) and optically stimulated luminescence (OSL) ages, the occurrence time of these transgressions were re-determined. The result showed that three major large-scale transgressions occurred separately at the beginning of marine isotopic stage 7 (MIS7), the last interglacial period (MIS5) and the Holocene. In addition, a small-scale transgression occurred in the mid-MIS6, and the corresponding transgressive stratum was deposited. The transgressive deposition of MIS3 was also discovered in this study. However, the characteristics of the foraminifera indicated the environment during this period was colder than that in the MIS5. By comparison with the global sea-level changes, the paleoenvironmental changes around the Bohai Sea in the late Quaternary can be consistent with the global climate changes.
... The second transgression (T-2) in the Bohai Sea is taken here as an example: in the classic pattern as first proposed by Zhao et al. (1978), T-2 was constrained to Marine Isotopic Stage (MIS) 3, mainly by radiocarbon dating and geomagnetic excursion events (e.g. IOCAS 1985;Zhao 1995;Wang & Tian 1999;Zhuang et al. 1999;Yan et al. 2006;Liu et al. 2009); in contrast, when dated by the luminescence method (Chen et al. 2008a;Yi et al. 2012) or magnetostratigraphy (Yao et al. 2006;Xiao et al. 2008;Shi et al. 2009), T-2 was adjusted to MIS 5 or even older. In the context that the global sea level was 60-80 m lower during 30-70 ka than at present (Chappell et al. 1996), Wang & Tian (1999) suggested that T-2 in MIS 3 was partially triggered by regional tectonic activity, whereas Yim et al. (1990) cited the young age bias of radiocarbon dates and claimed that the 'MIS 3 transgression' was significantly underestimated in Hong Kong. ...
... -Previous work has identified three major transgressive events around the marginal seas of China related to the late Pleistocene, including the (Upper and Lower) Cangzhou transgressions, the Xianxian transgression and the Huanghua transgression (e.g. Zhao et al. 1978;IOCAS 1985;Yim et al. 1990;Han et al. 1994;Zhao 1995;Zhang et al. 1996Zhang et al. , 2008aWang & Tian 1999;Zhuang et al. 1999;Yan et al. 2006;Yao et al. 2006;Chen et al. 2008a;Wang et al. 2008;Xiao et al. 2008;Shi et al. 2009;Liu et al. 2009Liu et al. , 2010bYi et al. 2012). According to lithofacies characteristics and down-core distributions of benthic foraminifera and grain size in the three cores studied here, together with comparison with the Shouguang E core (Zhao 1995) in Yao et al. (2010) and Yi et al. (2012), these major transgressive events could be related to the four marine/coastal sedimentary units, namely DU-7, DU-5, DU-3 and DU-1. ...
The alternation of terrestrial and marine deposits is an indicator of past environmental and sea-level changes. The age of deposition is usually dated by means of radiocarbon. However, radiocarbon dates of molluscan shells from coastal areas may be complicated by various sources of carbon, and problematic for deposits of 40–50 ka or older. Herein, we apply the Optically Stimulated Luminescence (OSL) dating method to date samples from terrestrial and marine/coastal sediments extracted from three cores in the south Bohai Sea, China. Multiple- and single-aliquot regenerative-dose procedures using OSL signals from fine-silt (4–11 μm), coarse-silt (38–63 μm) and fine-sand (63–90 or 90–125 μm) quartz were employed to determine the equivalent dose (D e). The results showed that: (i) OSL ages from quartz of different grain sizes and different protocols are consistent with each other; (ii) for Holocene samples, most of the radiocarbon dates agree well with OSL ages; (iii) for pre-Holocene samples, radiocarbon dates cluster at 40–50 14 C ka BP, whereas OSL ages are in stratigraphic order from 11 ka to 176 ka. Because of the self-consistency of the quartz OSL ages, the stratigraphic agreement in the three cores, and the clustering of the radiocarbon dates, we suggest that the quartz OSL ages are more reliable with respect to dating the samples from the south Bohai Sea. Finally, the four marine strata identified in the south Bohai Sea are likely to have formed during the Holocene, Marine Isotopic Stage (MIS) 3–5, MIS 6 and probably MIS 7, respectively.
... Sea level fluctuations caused by glacial-interglacial cycles are the dominant factor leading to transgression-regression and sedimentary structure changes in the Bohai Sea since the late Quaternary (Marsset et al., 1996;Shi et al., 2016). Four or three marine transgressions caused by global sea level changes have been found in the Bohai Sea (Fig. 12), corresponding to MIS 7, MIS 5, MIS 3 and MIS 1 (Qin et al., 1985;Yao et al., 2014;Shi et al., 2021) or MIS 7, MIS 5 and MIS 1 (Shi et al., 2009;Yi et al., 2012;Gao et al., 2018). BH1302 also recorded three interglacial and one interstadial transgressions in the southern Bohai Sea since the late Quaternary. ...
... In addition, some sedimentary records from long cores in the Bohai Sea area could extend back to the lower Quaternary or upper Neogene (e.g., An et al., 1979;Qian, 1984;Zhuang et al., 1999;Yao et al., 2006;Xu et al., 2017Xu et al., , 2018. Different ages of the Quaternary initial transgression have been inferred from long sediment cores in different sites of the Bohai Sea area, including early Pleistocene at 2.26 Ma , 1.7 Ma (Qian, 1984;Wang et al., 2004), or 0.83 Ma (Liu et al., 2016b); or Middle Pleistocene at 0.5 Ma (Shi et al., 2009), 0.41-0.46 Ma (Zhuang et al., 1999), or 0.26 Ma (Yi et al., 2015). ...
The Bohai Strait connects the Bohai Sea with the Yellow Sea, allowing material and energy exchange between the seas. The sedimentary record in this region is important for reconstructing the Quaternary sea-level changes and environmental evolution in the Bohai Sea area; however, long sedimentary sequences with a reliable chronological framework from this area are scarce. We assessed the sedimentary characteristics, grain size, microfossils, accelerator mass spectrometry ¹⁴C ages and optically stimulated luminescence ages of core BHS01 from the Bohai Strait. From these and previous paleomagnetic results, new insights into regional sea-level changes and environmental evolution in the Bohai Strait over the last 2.25 Myr are obtained. The sedimentology and environmental proxies (benthic foraminifera and marine ostracods) indicate that the sedimentary environment of the area around core BHS01 was mainly dominated by fluvial–lacustrine deposits from 2.25 to 0.89 Ma, and subsequently by alternating marine and fluvial deposits. Comparative analyses of the chronological and sedimentary results of core BHS01 with previous drilling records in the eastern marginal seas of China revealed that the Quaternary initial marine transgression of the Bohai Sea occurred no later than 0.89 Ma (latest early Pleistocene) since Quaternary. The initial transgression presumably resulted from the partial subsidence and disintegration of the Miaodao Islands Uplift with sea-level rise during this period or slightly earlier. This result is generally consistent with the timing of the Quaternary regional marine transgressive processes of the Yellow and Bohai seas; thus, we propose a conceptual model in which the first marine transgression of the Yellow Sea and the Bohai Sea during the Quaternary occurred no later than 1.66 Ma and 0.89 Ma, respectively. This study provides new evidence for understanding the Quaternary sea-level changes and regional environmental evolution in the Bohai Sea.
... Based on the identification and definition of transgressive layers, evidence from deep-sea oxygen isotope curves shows that Early Pleistocene and Middle Pleistocene marine strata are consistent with an interglacial period (Li Xiaoyan et al., 2015). However, transgressive chronologies are focused mainly in the South Yellow Sea and the regions adjacent to the Bohai during the Quaternary (Shi Linfeng et al., 2009;Yi et al., 2012;Liu et al., 2016aLiu et al., , 2016b. Mentions of the Subei Basin are scarce in the literature Zhang Zhenke et al., 2010). ...
Sedimentary sequences in the Subei Basin are complex and have been affected by interactions between the ocean and rivers since the Late Pliocene, including the Yellow River, Huaihe River, and the Yangtze River. This sedimentary evolution, in particular the timing of Pleistocene transgressions, has long been a matter of controversy owing to the lack of precise chronological evidence. The aim of this study is to explore the evolution of the sedimentary environment throughout the past 3.00 Ma in this region on the basis of a comprehensive analysis of particle size and foraminifera and ostracods collected in the TZK9 core from the Subei Basin combined with geochronological studies of magnetostratigraphy, AMS14C and optically stimulated luminescence (OSL). The results show that fluvial facies in the sedimentary environment from 3.00 to 1.01 Ma. There were fluvial facies and reflects six sea‐level high stands from 1.01 to 0.25 Ma. The study area was affected by four large‐scale transgressions since 0.25 Ma. The four marine sedimentary layers known as DU7 (buried at 48–52 m), DU5 (buried at 35–41 m), DU3 (buried at 16–23 m), and DU1 (buried at 2–4 m) are recorded in the MIS7 (210–250 ka), MIS5, MIS3, and Holocene, respectively. The magnitude of the DU5 transgression was identical to that of the DU3 transgression, both were larger than the DU7 transgression, and the DU1 transgression was the weakest. The variation of transgression strength reflects the influence of global changes in sea level, tectonic subsidence, shell ridges, and sand dams. In the TZK9 core, we found evidence of seven sea‐level high stands from the Early–Middle Pleistocene, and the first one caused by regional rapid subsidence and could be traced back to 0.83‐0.84 Ma. The sea‐level high stands and the age of the first one recorded above was different from other cores in eastern China, this was caused by the lack of absolute age control and the differences in paleotopography during this period. This study reconstructs sedimentary evolution, determines the transgression and its age, establishes the chronology since the Late Pliocene, and provides a scientific framework for further paleoenvironmental and tectonic studies. The results of this study highlight the important role that local tectonics and global sea level play in the sedimentary evolution and transgressions that have occurred in the western Subei Basin.
... During the past two decades, numerous boreholes of Pliocene-Quaternary age have been obtained from the basin and they offer an excellent opportunity to establish a regional chronostratigraphic framework by integrating magnetostratigraphic dating with other chronostratigraphic data. In this study, we combine the new magnetostratigraphic results from the two boreholes cores with the previously published magnetostratigraphy of other boreholes cores from Bohai Bay, including CQJ4 (Shi et al., 2009), BZ1 (Xiao et al., 2008), BZ2 (Yao et al., 2010), G2 (Xiao et al., 2014), NY05 , BG10 , MT04 and TZ02 , in order to explore the regional structural characteristics during the interval from the Pliocene to the Quaternary. ...
The sediments of Bohai Bay Basin have recorded the processes of basin infilling and structural evolution, reflecting the destruction of the North China Craton during the late Mesozoic and the early Cenozoic. However, the absence of a reliable chronostratigraphic framework for the sedimentary sequences in the basin has precluded a comprehensive understanding of these processes. This is especially the case for southwestern Bohai Bay, the evolution of which has been affected by two Quaternary volcanoes, Dashan and Xiaoshan. In this study, we combine paleomagnetic and sedimentary analyses of the sediments from two boreholes (CK3 and G4) from southwestern Bohai Bay Basin in order to provide new insights into the sedimentary history and regional tectonic processes since the Pliocene. The main findings are as follows. (1) Magnetite and hematite are the main carriers of the characteristic remanent magnetization in these sedimentary sequences, with hematite the main component. (2) The two drill cores record the Brunhes, Olduvai and Gauss normal chrons, and the Matuyama and Gilbert reverse chrons. (3) Subsidence-related differences in the depths of the Matuyama/Brunhes (M/B) and Gauss/Matuyama (G/M) boundaries in boreholes across Bohai Bay, distributed within different structural units, reflect the fact that northern Bohai Bay is the regional subsidence center and that the development of the WNW-orientated structures of the basin has intensified during the Quaternary. (4) The trend of changes in the elevation of three marine layers is similar to that of the M/B and G/M boundaries across Bohai Bay. Based on magnetostratigraphic constraints of the boreholes, the ages of the second and third marine layers are assigned to Marine Oxygen Isotope (MIS) 3 and MIS 5, respectively. The WNW-orientated structures and ‘super interglacials’ resulted in the formation of transgressions in the Huanghua depression. (5) In borehole CK3, the ages of four volcanic layers at the depth intervals of 13.14–16.18 m, 33.37–48.02 m, 145.8–154.05 m and 222.16–233.80 m, are 10–18 ka BP, 80–90 ka BP, 2.2 Ma and 3.1 Ma, respectively. In borehole G4, the age of the volcanic layer at the depth of 46.4–55.8 m is 0.33–0.55 Ma. Comparative analysis of subsidence-related differences between the NEE and NE-orientated uplifts and depressions in western and southern Bohai Bay indicates that structural evolution in the vertical plane during the Quaternary was mainly controlled by the subduction of the Pacific Plate.
... Magnetostratigraphies for the coastal area of Bohai Bay are available for the following boreholes: Middle Huanghua depression, western Bohai Bay: CQJ4 in Banqiao sag (Shi et al., 2009), BZ1 in Banqiao sag (Xiao et al., 2008), and G2 in Beitang sag (Xiao et al., 2014). Northern Huanghua depression, northern Bohai Bay: BG10 in Nanpu sag , and MT04 in Matouying rise . ...
The sediments of Bohai Bay Basin in North China have recorded the processes of basin filling and structural evolution, which may have resulted from the destruction of the North China Craton during the late Mesozoic and early Cenozoic. However, the absence of a reliable chronostratigraphic framework for the sedimentary sequences in the basin has prevented a comprehensive understanding of these processes. In this study, we combine paleomagnetic and sedimentary analyses of the sediments from two new boreholes (NY05 and TZ02) from northern Bohai Bay to provide new insights into the sedimentary history and regional tectonic processes since the Pliocene. The main findings are as follows: (1) Magnetite and hematite are the main carriers of the characteristic remanent magnetization. (2) The boreholes record the Brunhes and Gauss normal chrons, and the Matuyama reversed chron. (3) Subsidence-related differences in the depths of the Matuyama/Brunhes (M/B) and Gauss/Matuyama (G/M) boundaries, sediment accumulation rates, and the sedimentary environments of the different tectonic units, enable us to identify that tectonic movements started in the Olduvai normal subchron and the development of the WNW-orientated tectonic features were intensified. (4) In the Huanghua depression, comparative analysis of subsidence-related differences between western and northern Bohai Bay indicates that the subsidence of the northern Bohai Bay may have been superimposed on the WNW-orientated tectonic activity and faulting associated with the collision between the Indian and the Eurasian Plates, in the context of localized subsidence.
... So far, long sedimentary records are rather sparse in the Bohai Sea. Although several studies have attempted to establish the chronology of the strata based on long cores in the Bohai Sea (Qin et al., 1990) and its adjacent coastal plain (Zhuang et al., 1999; Xiao et al., 2008; Shi et al., 2009; Yao et al., 2010), the low-resolution of the age models is insufficient to discuss sedimentation at glacial–interglacial timescales. In this study, a 212.4-m core (BH08) was recovered from the central Bohai Sea. ...
... F1, F2, F3 and F4 represent the components of V-PCA procedures and their variances are displayed.6. Regional comparison of the three transgressions around the Bohai Sea and the Yellow Sea. 1, Bc-1 (IOCAS, 1985); 3, CQJ-4 (Shi et al., 2009); 4, BZ-1 (Chen et al., 2008); 5, P-8 (Gao et al., 1986); 6, BQ-1 (Yan et al., 2006); 7, S-3 (Zhuang et al., 1999); 8, E (Zhao, 1995); 9, Lz908 (this study); 12, Qc-2 (Yang and Lin, 1991); 2 (B-5), 10 (L-2), 11 (GK-5), 13 (Qc-5) and 14 (HD) are modified from Wang and Tian (1999). The average grain size of E core (Zhao, 1995) and Lz908 core (this study) are also displayed for comparison. ...
The Bohai Sea was formed by subsidence during the Cenozoic. Some 2000–3000 m of fluvial, lacustrine and marine sediments has been deposited in this basin. Previous studies focused mainly on the transgression history, with little examination of orbital variation in relation to other areas within the Asian monsoon domain.Here, we present the late Quaternary results of a new borehole in the south Bohai Sea. Optically stimulated luminescence and radiocarbon dating, which provide concordant age estimates, were employed to generate an initial chronology for the borehole. After refining the chronology through astronomical tuning, the results showed that: (1) the grain size variation represents Asian monsoon intensity which was dominated by both solar insolation (major) and global ice volume (minor) forcing; (2) the magnetic susceptibility indicates river incision processes which were sensitive to orbital tilt with influence from solar insolation; (3) the vegetation coverage responded to global ice volume coupled obliquity changes; and that (4) neither external nor internal factors could dominate the paleoenvironmental evolution on orbital timescales in an independent way, and they are both integrated in a complex pattern. We conclude that three different astronomical rhythms have affected coastal evolution, and that the sedimentary records in the south Bohai Sea, China, result from the nonlinear interaction and the complex response to driving processes.
Sedimentary architecture dominated by transgression–regression cycles in the shallow Bohai shelf region con- tains information about global sea-level, climate and local tectonics. However, previous studies of trans- gression–regression cycles in this region at orbital timescales that extend back to the early Pleistocene are sparse. In this study, we present an integrated sedimentological, paleontological study of a 32.49 m (93kyr BP) core (HZK02) recovered from the Bohai Sea, China, for which an AMS 14C and five OSL dates-based age model is available. Compared with previous pollen study in the Bohai area, the results show that there were two sig- nificant transgressions that occur in MIS 5c, top part of MIS 2 and MIS 1, with abundant foraminifera from the near shore shallow sea of the continental shelf, corresponding with prevailing arboreal pollen dominated by Pinus and Quercus. While, terrestrial herbs such as Artemisia and Chenopodiaceae dominated during colder periods, such as MIS 4, MIS 5b, when sea levels dropped significantly, corresponding with a scarcity of foraminifera in terrestrial sediment layers from MIS 5b, MIS 5a, MIS 4, and MIS 3. We find that at depth of 8.18–6.10 m, with depth of only 2.08 m and very high sediment rate, the duration age last from 64,100 yr BP to 10,500 yr BP, which might indicate some missing part of the deposition of MIS 3 and MIS 2. The transgressions signal has been found in top part of MIS 2 sediment, hardly in MIS 3.
The Bohai Sea is a typical shelf sea, with obvious sediment differences in different regions. Although Liaodong Bay is the largest bay in the Bohai Sea, there lacks boreholes with precise dating. In this paper, the core sediments taken from YKC-2 borehole in the northeastern of Liaodong Bay are dated with AMS¹⁴C and OSL, in addition to grain size analysis, foraminifera and pollen identification, lithological characteristics and other testing results. Correlation is made with the global sea level change curve, and upon the basis the evolution of paleoenvironment in the northeast of Liaodong Bay is reconstructed. It is speculated that the age of the bottom of borehole YKC-2 is 150 kyr B.P., and two transgressions have been recorded, similar to the situation in JXC-1, a borehole 46.7 km to the west. It can be found that the sedimentation rate of YKC-2 borehole is obviously higher than that of JXC-1. The authors’ research found that it is mainly controlled by two factors: the provenance difference and the differential movement of basin controlling faults. In the west, sediments are mainly transported by the Bohai Sea current, with insufficient sediment supply, and the basin-controlling faults are rather stable and very weak in activity. In the east, sediments are transported mainly by the surrounding rivers with sufficient sediment supply; and the changes in accommodation space are under the control of the Tan-Lu fault zone. Affected by the strong extensional dynamic environment of the Bohai Bay Basin, the accommodation space, where the borehole YKC-2 is located, continuously increased for deposition of near-source river sediments. This article is an endeavor to study the evolution of the Late Quaternary sedimentary environment and the influence of tectonic activity on Quaternary sedimentation in the Bohai Sea.
The thick Cenozoic sequence of alluvial, lacustrine, volcaniclastic, and marine sediments in the Bohai Bay Basin (BBB) of eastern China is an important sedimentary archive for studying the regional Late Cenozoic history of volcanism, tectonism, and paleoclimate changes, as well as the evolution of the East Asian monsoon system. However, well-dated deep drillcores are sparse in this region, which has prevented a comprehensive analysis of these issues. Here, we present the results of a detailed magnetostratigraphic and magnetic susceptibility study of two deep drillcores (G2 and G3) from the Huanghua Depression, with the aims of (1) refining the upper Miocene-to-Recent chronostratigraphic framework and subsidence history of the BBB, and (2) investigating its relationship to regional volcanic and tectonic events. The observed pattern of paleomagnetic polarity zones in Core G3 can be correlated well to the geomagnetic polarity time scale (GPTS). Quaternary-age peaks in the magnetic susceptibility profiles of Cores G2 and G3 may record large volcanic eruptions―they can be matched to similar peaks in other BBB drillcores, demonstrating their potential utility as regional marker horizons. Increased sedimentation rates in the study cores at ~8.0–6.4 Ma and 3.6–3.0 Ma reflect late Miocene uplift of the Taihang and Lvliang Mountains and late Pliocene BBB subsidence, respectively. Integrated into a regional framework for the upper Miocene to Recent, our magnetostratigraphic data show that subsidence of the Huanghua Depression increased from southwest to northeast.
The Bohai Basin was transformed to an inner shelf sea hundreds of thousands years ago. This youngest land-sea transition participated in the significant modification of the distribution of fresh water, sediment fluxes and climate in East Asia, and played an important role in the origin of the Asian marginal seas. Here we present the results of a magnetostratigraphic investigation and propose a conceptual model for the land-sea transition. Our findings indicate that the transition probably started several million years ago, from a fluvial system during the late Miocene and early Pliocene, to a lacustrine environment between the late Pliocene and Middle Pleistocene, and finally to a marine system in the late Pleistocene. Comparison of our results with previous research suggests that the Bohai Paleolake was initiated from the late Pliocene, was fully developed prior to ~1.0 Ma, and terminated around the late Middle Pleistocene. The Miaodao Islands formed the eastern “barrier” of the basin and since the Pliocene or earlier they played a significant role in blocking the lake water and sediments. They deformed from ~1.0 Ma, subsided significantly at ~0.3 Ma and completely by ~0.1 Ma, resulting in the maturation of the basin as an inner shelf sea.
Two 80 meters deep boreholes (BT113 and BT114) were carried in the west coast of Bohai Bay in order to clarify the revolution of sedimentary environments. Three marine sedimentary beds were identified based on sediment composition and texture, faunal assemblages (mollusk, benthic foraminifera and ostracoda) as well as AMS 14C and OSL ages. According to their order, from bottom to top, they are interpreted as Marine Bed 3(M3) deposited in the Later Mid-Pleistocene, Marine Bed 2(M2) in the Late Pleistocene and Marine Bed 1(M1) in the Holocene. These marine beds, from M3 to M1, reveal three major sea level movements since the Late Mid-Pleistocene. M3, M2 and M1, corresponding to marine facies deposited in MIS(marine isotope stage) 7, MIS5, and MIS1, respectively, indicate the repeated highstands during those periods. Therefore, it can be conclude that the development of these marine beds recording the regional sea level trends in the west coast of Bohai Bay, is well accordant with the global change. Different from the previous studies, authors consider that the marine transgression which controlled sea water to intrude into the Bohai Sea did not impact the studied area during MIS3 due to the relative lowstand and shallow topography of Bohai Strait. Contrastive analysis of multi boreholes indicates that the three marine beds are distributed widely and comparable well in the west coast of Bohai Bay. Changeable elevation and thickness of the marine beds within different boreholes imply that there have happened differential depressional movements during the Late Pleistocene period.
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