New insights on the origin of the basement of the Xisha Uplift, South China Sea
New insights on the origin of the basement of the Xisha Uplift, South China Sea
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南海西沙隆起基底成因新认识
DOI：
10.1007/s11430-017-9089-9
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发表时间：
2017-09
期刊：
影响因子：
--
通讯作者：
Shao L
中科院分区：
文献类型：
--
作者：
Zhu W L;Xie X N;Wang Z F;Zhang D J;Zhang C L;Cao L C;Shao L
基底地质年代学的研究为海洋构造演化提供了重要的信息。然而，早期对西沙盆地基底的研究受到有限的地球物理和地震资料的限制;西永1号是20世纪70年代钻探的唯一一个商业性钻孔，因为大陆边缘上覆新生代地层厚度巨大。本文利用XK 1钻孔新获得的两个基底样品，通过岩石学分析和锆石U-Pb同位素测年资料，加深了对西沙盆地基底形成和构造特征的认识。结果表明，该基底由晚侏罗世角闪石斜长片麻岩组成，锆石206 Pb/238 U平均年龄为152.9± 1.7Ma。然而，这些岩石的最年轻年龄（137±1 Ma）也表明西沙基底内的变质作用终止于早白垩世。这些变质岩之下有二长花岗岩，是早白垩世晚期（107.8± 3.6Ma）岩浆侵入形成的。因此，在对比的前寒武纪年龄（散装铷（Rb）-锶（Sr）分析，627马）建议由以前的工作在附近的西永1钻孔，锆石XK 1可能是晚中生代岩浆活动的产物。晚侏罗世-早白垩世区域变质作用和花岗质侵入体不局限于西沙;在珠江口盆地和南沙群岛等地区也有岩石记录（南沙群岛），因此可能与东亚大陆边缘下的古太平洋板块的大规模和长期俯冲密切相关，可能是南海中特提斯洋闭合的结果。关于南海地区最初是否是在一个统一的前寒武纪变质结晶基底上发展起来的，至今仍存在争议。然而，很明显，到这个时候，中生代的挤压俯冲和新生代的裂谷和伸展作用已经显著地改变了南海地区的原始基底。
The study of basement geochronology provides crucial insights into the tectonic evolution of oceans. However, early studies on the basement of the Xisha Uplift were constrained by limited geophysical and seismic data; Xiyong1 was the only commercial borehole drilled during the 1970s because of the huge thickness of overlying Cenozoic strata on the continental margin. Utilizing two newly-acquired basement samples from borehole XK1, we present petrological analysis and zircon uranium (U)-lead (Pb) isotope dating data in this paper that enhance our understanding of the formation and tectonic features of the Xisha Uplift basement. Results indicate that this basement is composed of Late Jurassic amphibole plagiogneisses that have an average zircon206Pb/238U age of 152.9±1.7 Ma. However, the youngest age of these rocks, 137±1 Ma, also suggests that metamorphism termination within the Xisha basement occurred by the Early Cretaceous. These metamorphic rocks have adamellites underneath them which were formed by magmatic intrusions during the late stage of the Early Cretaceous (107.8±3.6 Ma). Thus, in contrast to the Precambrian age (bulk rubidium (Rb)-strontium (Sr) analysis, 627 Ma) suggested by previous work on the nearby Xiyong1 borehole, zircons from XK1 are likely the product of Late Mesozoic igneous activity. Late Jurassic-Early Cretaceous regional metamorphism and granitic intrusions are not confined to Xisha; rocks have also been documented from areas including the Pearl River Mouth Basin and the Nansha Islands (Spratly Islands) and thus are likely closely related to large-scale and long-lasting subduction of the paleo-Pacific plate underneath the continental margins of East Asia, perhaps the result of closure of the Meso-Tethys in the South China Sea (SCS). Controversies remain as to whether, or not, the SCS region developed initially on a uniform Precambrian-aged metamorphic crystalline basement. It is clear, however, that by this time both Mesozoic compressive subduction and Cenozoic rifting and extension had significantly modified the original basement of the SCS region.
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DOI：
--
发表时间：
2011
期刊：
Chinese Journal of Geophysics
影响因子：
--
作者：
H. Hai;Qiu Xue
通讯作者：
H. Hai;Qiu Xue
影响因子：
1.5
作者：
Di Zhou;Zhen Sun;Han-zong Chen;He‐hua Xu;Wan‐yin Wang;X. Pang;Dongsheng Cai;D. Hu
通讯作者：
Di Zhou;Zhen Sun;Han-zong Chen;He‐hua Xu;Wan‐yin Wang;X. Pang;Dongsheng Cai;D. Hu
影响因子：
--
作者：
S. Nissen;D. Hayes;Yao Bochu;W. Zeng;Yong-shun Chen;Xiaupin Nu
通讯作者：
S. Nissen;D. Hayes;Yao Bochu;W. Zeng;Yong-shun Chen;Xiaupin Nu
影响因子：
4.2
作者：
H. Kudrass;M. Wiedicke;P. Čepek;H. Kreuzer;P. Müller
通讯作者：
H. Kudrass;M. Wiedicke;P. Čepek;H. Kreuzer;P. Müller
DOI：
--
发表时间：
2005
期刊：
--
影响因子：
--
作者：
Liu Hai-ling;C. Key
通讯作者：
Liu Hai-ling;C. Key