Along-strike breakup variations of the continent-ocean transition zone in the northern South China Sea

Xi Peng, Chun-Feng Li
{"title":"Along-strike breakup variations of the continent-ocean transition zone in the northern South China Sea","authors":"Xi Peng, Chun-Feng Li","doi":"10.1144/jgs2023-134","DOIUrl":null,"url":null,"abstract":"To understand breakup styles and syn-rifting magmatism in the northern South China Sea (SCS), we analyze how the continent-ocean transition zone (COT) varies along strike in its potential field and deep structures. High free-air gravity anomaly and accompanied basement structures evidence significant mantle upwelling and serpentinization in the northeastern COT. The top basement of the COT is uplifted and rough, but gradually retrogrades into a relatively flat and low relief towards the mid-northern margin, where reduced gravity anomaly reflects subdued mantle upwelling but perhaps stronger syn-rifting magmatism. In the northwestern margin, low gravity anomaly suggests fairly limited mantle upwelling, but more syn-rifting magmatic intrusions in the crust, and the top basement of the COT is smooth and slightly deepened. The COT widths are mostly less than 30 km, and within the COT the oldest legible magnetic anomaly C11r is related to the final continental breakup. The seaward limit of the COT should be relocated further south beyond anomaly C11r, pointing to a very narrow zone of true oceanic lithosphere in the Northwest Subbasin. The coexistence of mantle upwelling/serpentinization, magmatic underplating, and volcanisms atop the COT during continental breakup characterizes a typical intermediate rifted margin that shows, nonetheless, significant along-strike variations.\n \n Thematic collection:\n This article is part of the Emerging knowledge on the tectonics of the South China Sea collection available at:\n https://www.lyellcollection.org/topic/collections/south-china-sea\n","PeriodicalId":507891,"journal":{"name":"Journal of the Geological Society","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2024-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of the Geological Society","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1144/jgs2023-134","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0

Abstract

To understand breakup styles and syn-rifting magmatism in the northern South China Sea (SCS), we analyze how the continent-ocean transition zone (COT) varies along strike in its potential field and deep structures. High free-air gravity anomaly and accompanied basement structures evidence significant mantle upwelling and serpentinization in the northeastern COT. The top basement of the COT is uplifted and rough, but gradually retrogrades into a relatively flat and low relief towards the mid-northern margin, where reduced gravity anomaly reflects subdued mantle upwelling but perhaps stronger syn-rifting magmatism. In the northwestern margin, low gravity anomaly suggests fairly limited mantle upwelling, but more syn-rifting magmatic intrusions in the crust, and the top basement of the COT is smooth and slightly deepened. The COT widths are mostly less than 30 km, and within the COT the oldest legible magnetic anomaly C11r is related to the final continental breakup. The seaward limit of the COT should be relocated further south beyond anomaly C11r, pointing to a very narrow zone of true oceanic lithosphere in the Northwest Subbasin. The coexistence of mantle upwelling/serpentinization, magmatic underplating, and volcanisms atop the COT during continental breakup characterizes a typical intermediate rifted margin that shows, nonetheless, significant along-strike variations. Thematic collection: This article is part of the Emerging knowledge on the tectonics of the South China Sea collection available at: https://www.lyellcollection.org/topic/collections/south-china-sea
南海北部大陆-海洋过渡带的沿线断裂变化
为了了解中国南海北部的断裂方式和同步断裂岩浆活动,我们分析了大陆-海洋过渡带(COT)在其潜在场和深部结构中如何沿走向变化。高自由空气重力异常和伴生的基底构造证明了大陆-海洋过渡带东北部存在显著的地幔上涌和蛇绿岩化现象。COT 顶部基底隆起且粗糙,但在中北缘逐渐回缩为相对平坦的低地形,重力异常的降低反映了地幔上升流的减弱,但同步断裂岩浆活动可能更强。在西北边缘,低重力异常表明地幔上升流相当有限,但地壳中有更多的同步断裂岩浆侵入,COT 的顶部基底光滑且略有加深。COT 宽度大多小于 30 公里,COT 内最古老的磁异常 C11r 与最终的大陆断裂有关。COT 的向海界限应在异常 C11r 之后进一步向南移动,这表明西北分盆地真正的大洋岩石圈区域非常狭窄。在大陆解体过程中,COT顶部地幔上涌/蛇绿岩化、岩浆下沉和火山活动并存,是典型的中间裂谷边缘的特征,但沿走向变化显著。 专题集:本文是《南海构造新知》文集的一部分,可登录 https://www.lyellcollection.org/topic/collections/south-china-sea 查阅。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
求助全文
约1分钟内获得全文 求助全文
来源期刊
自引率
0.00%
发文量
0
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
copy
已复制链接
快去分享给好友吧!
我知道了
右上角分享
点击右上角分享
0
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术官方微信