| LIU Hanyao,LIN Changsong,ZHANG Zhongtao,ZHANG Bo,JIANG Jing,TIAN Hongxun,LIU Huan. 2019. High-resolution sequence architecture and depositional evolution of the Quaternary in the northeastern shelf margin of the South China Sea. Acta Oceanologica Sinica, 38(5):86－98 |
| High-resolution sequence architecture and depositional evolution of the Quaternary in the northeastern shelf margin of the South China Sea |
| 南海东北部陆架边缘第四纪高分辨率层序地层和沉积体系演化及其控制因素 |
| Received:December 05, 2017 |
| DOI：10.1007/s13131-019-1442-2 |
| Key words:sequence architecture depositional systems continental slope Quaternary Zhujiang (Pearl) River Mouth Basin |
| 中文关键词: 层序格架 沉积体系 陆架斜坡 第四系 珠江口盆地 |
| 基金项目:The National Natural Science Foundation of China under contract Nos 91328201, 91528301 and 41130422. |
| Author Name | Affiliation | E-mail | | LIU Hanyao | School of Ocean Sciences, China University of Geosciences, Beijing 100083, China | | | LIN Changsong | School of Ocean Sciences, China University of Geosciences, Beijing 100083, China | lincs58@163.com | | ZHANG Zhongtao | Shenzhen Branch of CNOOC Ltd., Guangzhou 518000, China | | | ZHANG Bo | Shenzhen Branch of CNOOC Ltd., Guangzhou 518000, China | | | JIANG Jing | School of Ocean Sciences, China University of Geosciences, Beijing 100083, China | | | TIAN Hongxun | School of Ocean Sciences, China University of Geosciences, Beijing 100083, China | | | LIU Huan | School of Ocean Sciences, China University of Geosciences, Beijing 100083, China | |
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| Abstract: |
| The northeastern shelf margin of the South China Sea (SCS) is characterized by the development of large scale foresets complexes since Quaternary. Based on integral analysis of the seismic, well logging and paleontological data, successions since~3.0 Ma can be defined as one composite sequence, consist of a set of regional transgressive to regressive sequences. They can be further divided into six 3rd order sequences (SQ0-SQ5) based on the Exxon sequence stratigraphic model. Since~1.6 Ma, five sets of deltaic systems characterized by development of wedge-shaped foresets complexes or clinoforms had been identified. High-resolution seismic data and the thick foresets allowed further divided of sub-depositional sequences (4th order) of regression to transgression, which is basically consistent with published stacked benthic foram O-isotope records. Depositional systems identified in the study area include deltaic deposits (inner-shelf deltas and shelf-edge deltas), incised valleys, and slope slumping massive deposits. Since~1.6 Ma, clinoforms prograded from the southern Panyu Lower Uplift toward the northern Baiyun Depression, shelf slope break migrated seaward, whereas the shelf edge of SQ0 migrated landward. The development of incised valleys in the continental shelf increased upward, especially intensive on the SB3 and SB2. The slumping massive deposits increased abruptly since SB2, which corresponds to the development of incised valleys. The evolution of depositional systems of continental slope mainly controlled by the combined influence of sea level changes, tectonic movements, sediment supply and climate changes. Since~3.0 Ma, relative sea level of the northern SCS had been experienced transgression (~3.0 Ma BP) to regression (~1.6 Ma BP). The regional regression and maximum transgressions of the composite sequences were apparently enhanced by uplift or subsidence related to tectono-thermal events. In addition, climatic variations including monsoon intensification and the mid-Pleistocene transition may have enhanced sediment supply by increasing erosion rate and have an indispensable influence on the development of the incised valleys and 5 sets of deltaic systems since~1.6 Ma. |
| 中文摘要: |
南海东北部陆架边缘第四纪以来发育大套以巨厚高角度前积层为特征的大陆斜坡沉积体系。依据地震、测井及微体古生物等资料详细分析，研究区从约3.0Ma以来被认为是一个复合层序，包括一套完整的海侵到海退旋回。依据Exxon的层序地层模型，这些层序可以进一步划分为6个三级层序（SQ0-SQ5）。自约1.6Ma以来，研究区可以识别出5套三角洲沉积体系，以S型前积复合体的发育为特征。高分辨率的地震数据及巨厚的前积地层进一步允许了四级层序海退-海侵旋回的划分，四级层序变化与底栖有孔虫氧同位素记录具有较好的对应关系。
研究区第四系识别出沉积体系包括三角洲沉积（内陆架三角洲，陆架边缘三角洲）、下切谷和斜坡滑塌沉积等。自约1.6Ma以来，研究区大陆斜坡沉积复合体（clinoforms）沉积由番禺低隆起南部不断向白云凹陷北部推进，陆架坡折总体向海迁移，而SQ0开始陆架边缘向陆迁移。陆架区下切谷向上不断发育，于SB3和SB2界面之上最为密集。斜坡滑塌沉积发育范围自SB2骤增，与下切谷的发育相响应。
大陆边缘沉积体系演化主要由海平面变化，构造运动，沉积供应和气候变化共同控制。自约3.0Ma以来，南海北部相对海平面经历了海侵（约3.0Ma开始）到海退（约1.6Ma开始）的过程。第四系复合层序的区域海退和最大海侵明显被构造沉降运动加强。此外，气候变化包括季风的强化作用和中更新世转型可能加强了剥蚀速率和沉积供给，对研究区约1.6Ma以来下切谷和5套三角洲的发育有着重要的控制作用。 |
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