Quaternary seismic facies of the South Yellow Sea shelf: depositional processes influenced by sea‐level change and tectonic controls

Abstract

The South Yellow Sea (SYS) is a semi-closed epicontinental sea, where voluminous material input and regional tectonic subsidence facilitate preservation of depositional strata, making it an ideal place for studying the regional responses to global sea-level changes during the Quaternary. Based on high-resolution single-channel seismic data, we conducted a detailed study of the SYS shelf in terms of its stratigraphic architecture and seismic facies. In combination with borehole data, we analysed the depositional processes of the SYS shelf since the Quaternary. A minimum of 14 seismic sequences were identified on the seismic profiles, which primarily show four typical seismic reflection facies: progradational reflection facies, parallel reflection facies, chaotic reflection facies and incised valley facies, with the former two seismic facies usually alternating with the latter two vertically. Borehole and seismic data revealed that the SYS shelf has been basically controlled by global sea-level changes since the Quaternary, and three significant transgression events had occurred over the SYS shelf since the Middle Pleistocene (ca. 730 ka BP-Present), taking place in the early Middle Pleistocene, the early Late Pleistocene and at the end of the Late Pleistocene-Holocene, respectively, with their products corresponding to seismic sequences U90, U50 and U10, respectively. Seismic data showed that, in a previous division of the main boundaries for holes EY02-2, NHH01 and QC2, the Holocene and the Upper Pleistocene bottom boundaries are concordant, while the Middle Pleistocene bottom boundary is discordant, and our study indicated that the division scheme for the Middle Pleistocene bottom boundary related to holes EY02-2 and NHH01 is more reasonable. The turning point of variation in the depositional environment of the SYS is at the end of the Middle Pleistocene, before which global sea-level change and tectonic subsidence controlled the shelf deposition. The shelf was inclined westwards and the tectonic topography of the southern margin of the shelf-forced seawater to invade via passages during sea-level rise. This resulted in a limited stratigraphic distribution formed by shortduration transgression events with low-amplitude sea-level rise; thereafter, the shelf deposition was predominated by global sea-level and rivers, and the shelf sediments were mainly derived from mainland China on the west of the shelf and were primarily accumulated on the middle and western parts of the shelf.

New findings on palynofacies characteristics of semi-enclosed deep-sea environments in the East Sea over 2 million years

“…50–60 Ma, causing the Yellow Sea Basin to maintain its continental environments up to the Pleistocene 43 , 44 . Fluvial deposits from several cores, including CSDP-1 on the Yellow Sea Basin until the late Pleistocene, also suggest that the SYS included continental/fluvial environments up to this period 19 , 44 – 47 . Moreover, the Zhe-Min uplift (ZMU), which extends from southern China to the western part of the Jeju Strait along the Jingshan–Shaoxing–Gwangju Fault, and was high terrain until the late Pleistocene, played the role of a partial barrier, preventing the intrusion of seawater from the East China Sea 44 , 46 .…”

“…Most terrestrial sediments transported by currents into the East Sea originate from the Yangtze River and the western and southern sea shelves of the KP and flow into the East Sea through the Jeju Strait (JS) and KS [12][13][14][15][16][17][18] . The continental shelf of the South Yellow Sea [SYS; less than about 100 m below the sea floor (mbsf)] is composed of paleochannels and river mouths, including those of the Yangtze River 19,20 . The southern sea shelf of the KP is composed of a narrow shelf less than 100 m deep connected to the Seomjin and Nakdong river mouths.…”

Caracterização Das Principais Feições Superficiais De Fundo E Em Subsuperfície No Limite Sudoeste Da Baía De Macapá, Canal Do Norte, Rio Amazonas

“…Na Baía de Macapá, a resposta sedimentar em superfície pode ser associada às formas de leito, enquanto que, em subsuperfície destacam-se a presença de sismofácies com características distintas em relação ao desenvolvimento das estruturas (Jaeger and Nittrouer, 1995;Li et al, 2016). Além disso, esta diversidade também está associada à alteração no padrão de sedimentação provocado pela: hidrodinâmica com a alteração dos valores de correntes e circulação estuarina; variação granulométrica; e espacialização das estruturas, as quais podem estar sujeitas a maiores intensidades de correntes como áreas próximas aos canais ou menores intensidades como margens e áreas adjacentes às ilhas ou bancos expostos em maré baixa (Fernandes et al, 2007;Strasser, 2002).…”

“…características são consideradas as principais responsáveis pela disposição dos refletores (Gomes et al, 2014;Li et al, 2016).…”

Preface: Earth system evolution of the Pacific and Indian oceans and the South China Sea

“…() concluded using Ce and Eu anomalies in the sediment cores that the Shikoku Basin, NW Pacific is characterized by hemipelagic and pelagic sedimentation. X.S. Li et al .…”