海洋地质前沿2025，Vol.41Issue(10)：38-49,12.DOI:10.16028/j.1009-2722.2024.250
基于重震联合反演的琼东南盆地下地壳高密度异常识别
Gravity-seismic joint inversion of high-density anomaly identification of lower crust in the Qiongdongnan Basin
摘要
Abstract
The Qiongdongnan Basin is located at the western end of the northern continental margin of the South China Sea.Compared to the active magmatism observed in the northeastern margin,its deep magmatic activity is relatively subdued,resulting in a lack of evidence for high-velocity anomalies typically associated with lower crustal underplating.To investigate the intensity and extent of deep mantle upwelling beneath the Qiongdongnan Basin under weak magmatic conditions,we employed a joint gravity-seismic inversion method to construct the crustal density structure and analyze the origin of high-density anomalies.Results reveal the presence of high-density anomalous bodies in the lower crust(below 20 km depth)and upper mantle beneath the central part of the basin,with densities ranging from 2.90-2.96 g/cm3 to 3.34-3.40 g/cm3,respectively.Correspondingly,the crust in this region exhibits extreme thinning,decreasing from 26 km at the continental margin to＜10 km in the central area,with the thinnest section measuring only 5 km.Additionally,the whole-crustal stretching factor exceeds 3.0,indicating hyper-extensional thinning characteristics.Integrated with previous studies,we infer that the Qiong-dongnan Basin underwent widespread crustal hyper-extension during the rifting phase,triggering extensive mantle upwelling and lower crustal underplating,which contributed to the formation of high-density anomalies in the lower crust.Due to their relatively small scale and weak magmatic signature,these features pose significant chal-lenges for seismic detection.Therefore,the gravity-seismic joint inversion method proves crucial for identifying deep mantle upwelling and lower crustal underplating in low-magma-activity settings,providing key insights into the formation and evolution mechanisms of the South China Sea as well as its magmatic processes.关键词
琼东南盆地/弱岩浆背景/岩浆活动/重震联合反演/高密度异常Key words
Qiongdongnan Basin/weak magma background/magmatism/gravity-seismic joint inversion/high density anomalies分类
海洋科学引用本文复制引用
葛佳裕,李朝阳,曹淑鑫,刘洪芹,赵俐红,张金伟,李忠华..基于重震联合反演的琼东南盆地下地壳高密度异常识别[J].海洋地质前沿,2025,41(10):38-49,12.基金项目
国家自然科学基金(42406077) （42406077）
山东省自然科学基金(ZR2022QD087) （ZR2022QD087）
海底科学与探测技术教育部重点实验室开放基金课题(SGPT-2020OF-04) （SGPT-2020OF-04）
福建省海洋物理与地质过程重点实验室开放基金课题(KLMPG-23-02) （KLMPG-23-02）
