Xiting Liu
Daidu Fan
Fangjian Xu
J. Paul Liu- 1Key Laboratory of Submarine Geosciences and Prospecting Technology, College of Marine Geosciences, Ocean University of China, Qingdao, China
- 2Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- 3State Key Laboratory of Marine Geology, Tongji University, Shanghai, China
- 4College of Marine Science, Hainan University, Haikou, China
- 5Department of Marine, Earth and Atmospheric Sciences, North Carolina State University, Raleigh, NC, United States
Editorial on the Research Topic
Sedimentation on the continental margins: From modern processes to deep-time records
The continental margin, which connects land and sea (Figure 1), is a key area of land-sea interaction (Walsh and Nittrouer, 2009), with a sedimentation process closely related to tectonic activities, climatic conditions, oceanic dynamics, and human activities (Fan and Li, 2002; Xu et al., 2017; Syvitski et al., 2022). Therefore, sediments on the continental margin can record environmental evolution both in terrestrial source and marine depositional areas (Shang et al., 2018; Pei et al., 2020; Dong et al., 2021). The continental margin is also the main location for the mineralization of organic matter (McKee et al., 2004; Liu et al., 2022), which affects the global carbon cycle (Bianchi and Allison, 2009; Ren et al., 2019). Sedimentation on different types of continental margins exhibits unique characteristics, such as the broad shelf dominated by the large East Asian rivers and the narrow shelf fed by the mountainous rivers of East Africa (Liu et al., 2004; Liu et al., 2009; Liu et al., 2016; Liu et al., 2018; Xu et al., 2021); thus, comparative studies on specific types of continental margins are needed. However, the complexity of interpreting signals from sedimentation processes to depositional records has limited our understanding of different types of continental marginal sedimentation (Figure 1). To fill this gap, this topic integrates the research results of different geological backgrounds and different time scales to form a new understanding of the knowledge system of sedimentation on global continental margins.
FIGURE 1. Schematic diagram of the sedimentation process and depositional record on the continental margin.
This Research Topic collected 27 articles from 162 authors worldwide, including articles on modern sedimentary dynamics and biogeochemical processes, historical depositional records, and the impacts of human activity on sedimentation at the continental margins.
Modern sedimentation dynamics on continental margins
Xie et al. analyzed water levels, daily river discharge, and bathymetric data from the Qiantang Estuary, China, in 2015 and delineated the seasonal tidal evolution along the estuary. Based on the CTD profiles and mooring measurements of the Line W program in the North Atlantic at about 35°N/70°W, Fan et al. found that the internal wave strain variance over the slope was up to five times larger than that in the interior. According to analyses of the vertical variation of Rossby number, kinetic energy in the submesoscale range, and kinetic energy spectra, Li et al. suggested that submesoscale motions between the New Jersey Shelf and Bermuda are mainly confined within the surface mixed layer, with seasonality that is strong in winter and weak in summer. Sun et al. reconstructed the migration of the coastline and river channels in the Northern Bohai Sea during the last century based on clay minerals. Chen et al. first applied grain size trend analysis (GSTA) and end-member analysis (EMA) to 232 surface sediment samples in the deep-sea environment to reveal sedimentary dynamics around isolated carbonate platforms in the northern South China Sea. By summarizing and analyzing research in the shelf-slope region offshore in the northeast of Taiwan, Chiang et al. refined the morphology of the Huapinghsu Channel/Mienhua Canyon System and proposed a new idea to illustrate this channel/canyon system as a sediment conduit transporting sediments from rivers in western Taiwan to the southern Okinawa Trough.
Biogeochemical cycles in the sediments on continental margins
Bruni et al. used a combination of literature and new data to study the drivers and biogeochemical consequences of wave- and current-induced resuspension on organic carbon cycling in modern, oxygen-depleted, “semi-liquid ocean bottom” regions, such as the Benguela upwelling region. Zhu et al. discovered bottom water DO conditions of the coastal northern South China Sea in the 20 th century based on the sedimentary C28Δ22/Δ5,22 ratios of steroids and proposed that the net photosynthetic oxygen production outweighs source water- and warming-induced increasing deoxygenation in the study area. To determine the historical redox state in the hypoxic zone near the Changjiang River Estuary and its adjacent waters, Zhang et al. investigated the distribution and enrichment of Mo, U, and V in core 3050-2 and found a general oxic-suboxic environment since 2005. Wang et al. reported the spatial distribution of brGDGT-related indicators in surface sediments from the East China Sea and suggested that mixed sources of soil-derived brGDGTs were dominant, and that marine in situ brGDGTs were overprinted. Li et al. reported a significant contribution from lateral allochthonous organic matter from the mountainous river in hydrate-bearing sediments from three long sedimentary sites in the Shenhu area of the northern South China Sea. Zhang et al. illustrated the depth profiles of sedimentary wtCaCO3% from the West Pacific based on a newly compiled CaCO3 data set and a carbonate model. Zhang et al. performed a comprehensive study of a long-term organic carbon record over the past 380 kyr from sediment core St10-PC in the Northwest Pacific, which highlighted the important contribution of environmental redox conditions on organic carbon burial in the deep Northwest Pacific. Chen et al. analyzed the archaeal ammonia oxidation rate indicator GDGT-[2]/[3] ratio (Glycerol Dialkyl Glycerol Tetraether) from collected data profiles since the last glacial period in the northern South China Sea and reported higher ratios during the Holocene compared to those during the last glacial period.
Sedimentation in response to paleoclimatic and palaeoceanographic evolution
Ding et al. presented the first high-resolution grain-size record from Core CF1 in the Okinawa Trough and found the Kuroshio Current slow-down during 4.6–2.0 ka, followed by a quick enhancement after 2.0 ka with centennial-scale variabilities (500–700 years). Zhang et al. studied the sedimentological characteristics of the mud periphery area and reconstructed the sedimentary evolution at the east edge of the Central Yellow Sea Mud since MIS3a (45 ka). Zhang et al. used optically stimulated luminescence (OSL) dating and lithology of core YRD-1401 from the Yellow River delta to establish the late Quaternary sedimentary evolution of the southwestern coast of the Bohai Sea. Sang et al. used clay mineralogy, major-element geochemistry, and Sr-Nd isotopic compositions from Core MD05-2896 collected in the southern South China Sea to investigate the discrimination of sediment provenance and reconstruct a history of chemical weathering in the Mekong River basin over the last 45 ka. Wu et al. conducted a high-resolution rock magnetic investigation of the Holocene sediments of core DS01 collected near the West River channel in the head area of the Pearl River deltaic plain to study how the sea-level change, monsoon-driven discharge, and especially human activity since the late Holocene regulated regional environmental and sedimentary evolution. Rashid et al. studied the Late Pleistocene Labrador Sea depositional systems developed in front of ice streams and glacier outlets from the Laurentide Ice Sheet (LIS) using Huntec and 3.5 kHz seismic profiles and piston cores covering >1800 km of the eastern Canadian continental margin and the Labrador Basin. Li et al. studied a sediment core (ANT32-RA05C) collected from the continental slope of the Ross Sea, Antarctica by paleomagnetic and 230Th dating and geochemical properties and reported a relationship between paleoenvironmental processes and the Antarctic temperature since the Late Pleistocene. Lyu et al. investigated iron oxide mineral content and major element compositions of the oceanic red beds at Site U1433 to reveal the Miocene deep-sea oxidation environment of the South China Sea and its interaction with the West Pacific. Shi et al. refined the chronostratigraphy of the upper 160 m sedimentary succession from Hole U1501C using paleomagnetic measurements and cyclostratigraphic analysis of natural gamma radiation (NGR) data to produce a high-resolution 15.54 Myr age model. Li et al. retrieved a record of the East Asian Summer Monsoon by studying the color reflectance of coastal sediments in the south Bohai Sea, East Asia, demonstrating an integrated forcing of ice-sheet evolution and solar insolation in the East Asian Summer Monsoon in the late Quaternary. Liu et al. identified three facies from the Liangshan Formation successions in western South China, which belong to the coastal alluvial plain, estuary, and deltaic environments that followed the dry-to-wet climatic shifts.
Impacts of human activity on marginal sedimentation
Lee et al. analyzed foraminiferal records collected from the continental slope off southwestern Taiwan, reporting that the anthropogenic carbon signal in the West Pacific was not weaker than that recorded in the Atlantic over the last century. Dong et al. reported a 55-year sedimentary record from Songkhla Lake, Thailand, including a three-stage sedimentary and input history of trace metals under anthropogenic effects since 1964.
In summary, the articles collected on this topic cover comprehensive studies on the sedimentation process and related biogeochemical processes on the continental margins at different times and spaces, from the tropical marginal seas to the high latitude glacial-dominated margins. The research methods included sedimentologic, biogeologic, geochemical, and geophysical data analysis. Therefore, these studies of different types of continental marginal sediments are of great scientific significance to provide a better understanding of the earth’s surface process and the evolution of the earth’s environment.
Author contributions
XL: conceptualization, funding acquisition, writing–original draft preparation and reviewing and editing; DF: funding acquisition, writing–reviewing and editing; JL and FX: writing–reviewing and editing.
Funding
This Research Topic was supported by the National Natural Science Foundation of China (41976053, 41976070, and 42276060) and the Natural Science Foundation of Shandong Province (ZR2021YQ26). We are grateful for the support of the Frontiers team and reviewers.
Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Publisher’s note
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Keywords: continental margin, sedimentary process, paleoclimate, paleoceanography, human activities
Citation: Liu X, Fan D, Xu F and Liu JP (2023) Editorial: Sedimentation on the continental margins: From modern processes to deep-time records. Front. Earth Sci. 10:1048801. doi: 10.3389/feart.2022.1048801
Received: 20 September 2022; Accepted: 29 September 2022;
Published: 12 January 2023.
Edited and reviewed by:
Sabine Schmidt, Centre National de la Recherche Scientifique (CNRS), FranceCopyright © 2023 Liu, Fan, Xu and Liu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Xiting Liu, liuxiting@ouc.edu.cn