Origin of the Site U1504 alkaline basalts in the South China Sea continental margin: Insights on deep mantle diversity and subduction dynamics under continental arcs

doi:10.1130/B37471.1

	Sun, Liheng 1,2; Zhang, Yunying 1,2; Sun, Zhen 1,2; Miao, Xiuquan 1,2; Li, Ruilong 1,2; Zhang, Wanfeng 2,3
	Origin of the Site U1504 alkaline basalts in the South China Sea continental margin: Insights on deep mantle diversity and subduction dynamics under continental arcs
刊名	GEOLOGICAL SOCIETY OF AMERICA BULLETIN
ISSN号	0016-7606
	2024-05-16
卷号	136 期号:11-12 页码:5027-5038
DOI	10.1130/B37471.1
语种	英语
WOS研究方向	Geology
摘要	Alkaline basalts produced in continental arcs should contain information different from the arc tholeiite-calc-alkaline-series magmas, and their origin could provide unique constraints on deep mantle composition and material cycling. However, due to their sparse occurrence, alkaline basalts in continental arcs have not been studied thoroughly, which hinders our understanding of the mantle diversity and subduction dynamics under continental arcs. In this study, we present new 40Ar/39Ar ages, major and trace elements, and Sr-Nd-Hf isotopic data for the International Ocean Discovery Program Site U1504 alkaline basalts in the continental arc developed on the South China Block (SCB). These alkaline basalts were generated at ca. 121 Ma and display typical oceanic-island basalt geochemical characteristics. Their relatively high epsilon Nd(t) (3.5-3.7) and low (87Sr/86Sr)i (0.7034-0.7040) and La/Nb (0.5-1.0) values suggest that they were mainly derived from an asthenosphere mantle source. Compared to alkaline basalts in the SCB inland, U1504 alkaline basalts exhibit lower K2O/Na2O, Zr/ Sm, Zr/Y, epsilon Nd(t), and epsilon Hf(t) values, indicating the addition of minor sub-continental lithospheric mantle. The enrichment of Nb, Ta, light rare earth elements, and slight depletion of Zr, Hf, and Ti, as well as elevated Fe/Mn and Sm/Yb and low CaO, indicate that their mantle lithology was mainly garnet pyroxenite. Based upon these findings and previous studies, the garnet pyroxenite was probably formed by the interaction of upwelling asthenosphere with slab edges in the scenario of break-off of the Paleo-Pacific Plate, and such interaction diversified the mantle chemistry beneath continental arcs. In conjunction with other reported alkaline basalt data, it is proposed that the enriched asthenosphere mantle beneath the SCB had formed sequentially from inland to coastal since the late Mesozoic, and this may be related to lateral and vertical flow in the deep asthenosphere controlled by the break-off of subducted plates.
WOS记录号	WOS:001261205000001
收录类别	SCI
引用统计	被引频次：3[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.gig.ac.cn/handle/344008/83068
专题	同位素地球化学国家重点实验室
作者单位	1.Chinese Acad Sci, South China Sea Inst Oceanol, Key Lab Ocean & Marginal Sea Geol, Guangzhou 510301, Peoples R China 2.Southern Marine Sci & Engn Guangdong Lab Guangzhou, Guangzhou 511458, Peoples R China 3.Chinese Acad Sci, State Key Lab Isotope Geochem, Guangzhou Inst Geochem, Guangzhou 510640, Peoples R China
推荐引用方式 GB/T 7714	Sun, Liheng,Zhang, Yunying,Sun, Zhen,et al. Origin of the Site U1504 alkaline basalts in the South China Sea continental margin: Insights on deep mantle diversity and subduction dynamics under continental arcs[J]. GEOLOGICAL SOCIETY OF AMERICA BULLETIN,2024,136(11-12):5027-5038.
APA	Sun, Liheng,Zhang, Yunying,Sun, Zhen,Miao, Xiuquan,Li, Ruilong,&Zhang, Wanfeng.(2024).Origin of the Site U1504 alkaline basalts in the South China Sea continental margin: Insights on deep mantle diversity and subduction dynamics under continental arcs.GEOLOGICAL SOCIETY OF AMERICA BULLETIN,136(11-12),5027-5038.
MLA	Sun, Liheng,et al."Origin of the Site U1504 alkaline basalts in the South China Sea continental margin: Insights on deep mantle diversity and subduction dynamics under continental arcs".GEOLOGICAL SOCIETY OF AMERICA BULLETIN 136.11-12(2024):5027-5038.