Journal of Marine Systems 82 (2010) S3–S16 Contents lists available at ScienceDirect Journal of Marine Systems journal homepage: www.elsevier.com/locate/jmarsys Sedimentary development of the Pearl River Estuary based on seismic stratigraphy Cheng Tang a,b,⁎, Di Zhou a, Rudolf Endler c, Jinqing Lin d, Jan Harff c a Key Laboratory of the Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China b Yantai Institute of Coastal Zone Research for Sustainable Development, Yantai, 264003, China c Institut für Ostseeforschung Warnemünde, Rostock, D-18119, Germany d Guangzhou Marine Geology Survey, Guangzhou, 510320, China article info abstract Article history: The Pearl River Estuary in the Southern China was studied both by applying concepts of seismic stratigraphy Received 20 December 2006 to the interpretation of high resolution seismic profiles and by correlating with borehole records. The Received in revised form 20 June 2008 correlation between seismic facies and borehole stratigraphy of the estuary enables to propose a seismic Accepted 12 January 2010 stratigraphy model of the estuarine infill. The stratigraphy and evolution of the Holocene succession of the Available online 12 February 2010 estuary were reconstructed. The history of estuarine sedimentary development consists of five stages represented by 5 seismic units bounded by laterally sub-continuous seismic interfaces and being consistent Keywords: Pearl River Estuary with the 5 borehole subdivisions: (i) The basal stage deposits, represented by BU and the borehole section P, Holocene might represent the paleo Pearl River alluvial deposits in the Late Quaternary. (ii) The stage I deposits, Sequence stratigraphy represented by SU1 and the borehole section A, might be late glacial prodeltaic deposits that occurred during Seismic stratigraphy Marine Isotope Stage 3 highstand. (iii) The stage II deposits, represented by SU2 and the borehole section B, consist of relatively coarse-grained sediments deposited during the post glacial transgression about 20–10 ka BP. (iv) The stage III deposits (SU3 and the borehole section C) were generated when the rate of sea level rise decreased in ∼20–10 kz BP, which forced sediments to be deposited inside the estuary, where a tidal ravinement surface was characterized by strong erosions and channel formations in the outer zone of the estuary. (v) The stage IV deposits (SU4 and the borehole section D) are the infillings of the estuarine highstand progradation during the last 6000 yrs when the sea surface almost reached the present level. © 2010 Elsevier B.V. All rights reserved. 1. Introduction physiography, filling history, hydrologic regime, and sea level fluctuations (Dabrio et al., 2000; Yoo and Park, 2000; Lericolais Sequence stratigraphy has been systematized as a general et al., 2001; Milia and Giordano, 2002; Lobo et al., 2003; Liu et al., methodology for the reconstruction of stratigraphic framework 2004; Hori et al., 2004; Ridente and Trincardi, 2005; Tanabe et al., since the late 1980s (Vail, 1987). In the beginning of the 1990s, the 2006; Liu et al., 2007). sequence stratigraphic concept was used in incised valley successions High resolution seismic profiles allow us to obtain continuous comprise a wide range of facies and a number of widespread and geophysical records of the surficial sedimentary units in shallow mappable stratigraphic discontinuities (Dalrymple, et al., 1992; Allen water, which improves our understanding of the sedimentary record and Posamentier, 1993; Dalrymple and Zaitlin, 1994; Lessa et al., of sea level change, with special references in the Estuarine study (Yoo 1998). Present-day estuaries typically originated as fluvial incised and Park, 2000; Lobo et al., 2005; Ridente and Trincardi, 2005). As one valleys that formed during the late Pleistocene eustatic sea level fall of the key regions to study land–sea interactions, the Pearl River and were drowned during the subsequent Holocene sea level rise. Estuary (PRE) in the Southern China has been extensively studied in Plentiful research activities with implementation of sequence strati- fields including hydrology, chemistry, biology and geology since the graphic concept have been used in determining recent geological 1980s as a rapid urbanization and industrialization in the surrounding history of shallow water systems and for establishing a relationship Pearl River Delta (PRD) was developed. Regarding with geology, many between their long-term evolution and delta/estuarine/prodelta authors (e.g. Long, 1997; Davis, 1999; Liu et al, 2004; Owen, 2005; Yim et al., 2006) have studied the Late Quaternary deposits in the Pearl River Delta and northern South China Shelf using seismic reflection profiling and borehole data, but few PRE records have been addressed about Holocene sedimentary environment change. In particularly, the * Corresponding author. Yantai Institute of Coastal Zone Research, Yinhai Rd. 26, sedimentary history of the estuarine filling is still poorly understood, Mailbox 1488, Laishan, Yantai, China. 264003. Tel.: +86 535 6910565; fax: +86 535 fl 6910566. especially referring to effects of late Pleistocene sea level uctuations E-mail address: [email protected] (C. Tang). on the preservation potential of depositional sequences. 0924-7963/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jmarsys.2010.02.001 S4 C. Tang et al. / Journal of Marine Systems 82 (2010) S3–S16 The present study driven by issues mentioned above focuses on 2. Regional setting the stratigraphic model of the Pearl River Estuary. In this paper, we have a closer look at geometry and acoustic characteristics of the The Pearl River, the third longest river in China, is about 2216 km latest Pleistocene–Holocene sequence of the PRE and discuss long and comprises of the West, the North, and the East rivers (Fig. 1). depositional systems and their bounding surfaces on the basis of the The Pearl River drainage catchment covers a total area of approxi- conceptual framework of the sequence stratigraphic analysis. Main mately 453,000 km2 with an annual water discharge exceeding goals of the present work are: (1) to identify the seismic stratigraphic 300,000 million m3 and an annual sediment load of 87 million tons. architecture of the estuarine sedimentary fill; (2) to elaborate a About 18,000 million m3 discharge flow into the PRE, while 30 million Holocene sequence stratigraphic model based on the correlation tons of suspend sand go into the estuary by estimation (Zhao, 1990). between seismic facies and estuarine deposits. Data used in the study The PRE is located on the northern margin of the South China Sea are high resolution reflection profiles and sediment cores. between 21°20′ N–23°30′ N, and 112°40′ E–114°50′ E (see Fig. 2). Fig. 1. Location of Pearl River estuary and the Pearl River Delta (PRD) in Southern China. The graph. C. Tang et al. / Journal of Marine Systems 82 (2010) S3–S16 S5 Fig. 2. Locations of cores in the Pearl River Estuary with bathymetric depth. Base map and water depth data were overlaid after State Navigation channel chart of Zhujiang Kou and approaches in 2002. There are two deep channels from the mouth of the estuary up to the towards the estuary, reaching a maximum in the upstream of the PRE head of the estuary. The water depth increases from the north to the (Mao et al., 2004). Wave heights are usually less than 0.2 m within the south, 2.8 m in the upper estuary to 20 m at the estuary mouth (Xia, inner estuary, but up to 2.5 m during the typhoons season (Huang, 2005). 2000). The annual temperature of the PRE area varies from 22 to 22.5°C The basement of the Pearl River delta and estuary was formed in and annual precipitation is between 1500 and 2000 mm. The average Early Tertiary. The strong block-faulting in the Late Tertiary made the wind speed is about 2.0–4.5 m/s. Typhoon mostly happens between Pearl River basin a chessboard shaped. Three groups of faults trending June and October. The tides in the PRE mainly flow from the Pacific NW, NE, and W shaped the area into blocks. In the middle late oceanic tidal propagation through the Luzon strait (Ye and Preiffer, Pleistocene, deposition processes started to form today's delta plain 1990) with a mean tidal range between 1.0 and 1.7 m. The estuarine (Huang et al., 1982). hydrodynamics are commonly characterized as well stratified during the wet season and well mixed during the dry season with repect to 3. Data and methods the salinity field (Dong et al., 2004). The PRE is a low energy microtidal estuary with a mean range of 0.86 to 1.69 m. The surface About 1000 km of high resolution seismic profiles inside the PRE tidal currents are moderate with peak velocities mostly less than were obtained in 2001 by South China Sea Institute of Oceanology, 100 cm/s only taking one-third of that in the bottom waters. The flood Chinese Academy of Science (SCSIO), using GeoPulse and GeoChirp by current moves approximately in a south–north direction with quite Geoacoustic Corp. with a shot interval of 500 ms and a recording scale different velocities in the parts of shoal and trough. The average tidal of 1000 ms. The other 1000 km high resolution seismic profiles were range was small in the offshore waters and increases gradually obtained by the Guangzhou Marine Geology Survey (GMGS) in 2004 S6 C. Tang et al. / Journal of Marine Systems 82 (2010) S3–S16 and 2005, using a single channel seismic system Delph Seismic by Elics conducted by accelerator mass spectrometry (AMS) at the Institute Corp. with a 250 ms recording interval and 800 J source. Both seismic of Physics Radiocarbon Laboratory, Silesian University of Technology, data track lines are digitalized and shown on Fig.