气候变化领域集成服务门户(CCPortal): Late Cretaceous arc magma differentiation in southern Tibet: Evidence from zircon U-Pb chronology, mineralogy and geochemistry

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DOI	10.18654/1000-0569/2023.05.15
	Late Cretaceous arc magma differentiation in southern Tibet: Evidence from zircon U-Pb chronology, mineralogy and geochemistry
	Guan Qi; Zhang MinJie; Cao JunLin; Shi HongJiang; Li ZengSheng; Wang DuiXing
发表日期	2023
ISSN	1000-0569
EISSN	2095-8927
起始页码	1459
结束页码	1483
卷号	39 期号:5
英文摘要	Magmatism in orogenic belts reflects a series of geological processes from oceanic subduction to continental collision, and as a result, it contains important information about the formation and growth of the continental crust. Among different types of magmas, the subduction-related arc is considered to be the main mechanism of the continental crust growth. Here, we report geochronological and geochemical data of the tonalite and MME-host biotite monzogranite pairs in the Quxu-Gongar, southern Lhasa Terrane, to constrain the petrogenesis of this series of rocks and the evolution of arc magmas. Zircon U-Pb dating indicates that they were synchronously emplaced at 91 similar to 88 Ma. The biotite monzogranites are medium-K calc-alkaline (A/CNK = 0.77 similar to 0.99), with high SiO2(68.90% similar to 69.18%) and Al2O3 (15.21% similar to 15.48%), low MgO (1.15% similar to 1.16%) and Mg-# (similar to 44), and high Sr/Y ratios (60 similar to 82), whose characteristics are similar to those of a typical adakite. The mafic microgranular enclaves (MMEs) have SiO2 = 54.75% similar to 54.96%, MgO = 3.92% similar to 5.40% and Mg-# = 52 similar to 61, with negative Eu anomalies (delta Eu = 0.79 similar to 0.82). The quartz diorites are medium-K calc-alkaline rocks, exhibiting high Mg-# (44 similar to 48) and weakly Eu depletions (delta Eu = 0.68 similar to 0.81). All the biotite monzogranites, MMEs and quartz diorites have similar Sr-Nd isotopic compositions (initial Sr-87/Sr-86 = 0.703594 similar to 0.703939, epsilon(Nd) (t) = +4.6 similar to +4.8), with varying zircon epsilon(Hf) (t) values (+10.9 similar to +15.6). The analysis of mineral composition shows that the An contents of the zoning plagioclase in the biotite monzogranites and MMEs gradually decreases from core to rim, and there is no reverse zoning structures. The pyroxene in quartz diorites is clinopyroxene, and the analyzed hornblende is calc hornblende, and the biotite is magnesium biotite. In summary, the biotite monzogranites, mafic enclaves and syngenetic quartz diorites represent they are formed from derivations of the fractional crystallization of mantle-derived magmas at different stages : the quartz diorites were formed at the first stage by the fractional crystallization of pyroxene, Ti-Fe oxide and apatite of mafic magmas, and then they evolved as the parent magma; the MMEs could be cumulates at the early stage; while the biotite monzogranites represented the component of the residual melt after the MMEs were formed. Our study shows that the Gangdese magmatic belt experienced a wet fractional crystallization and cumulate during the Late Cretaceous, and the arc magma differentiation of subduction zones plays an important role in the formation and evolution of the continental crust.
关键词	Late Cretaceous Arc magma differentiation Southern Lhasa Terrane Tibet
英文关键词	CONTINENTAL COLLISION ZONES; GANGDESE BATHOLITH; MAGNESIAN ANDESITE; CRUST; ADAKITES; ENCLAVES; ORIGIN; AREA; ASTHENOSPHERE; ASSOCIATION
WOS研究方向	Geology
WOS记录号	WOS:000987256500015
来源期刊	ACTA PETROLOGICA SINICA
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/283052
作者单位	Hebei GEO University; Hebei GEO University
推荐引用方式 GB/T 7714	Guan Qi,Zhang MinJie,Cao JunLin,et al. Late Cretaceous arc magma differentiation in southern Tibet: Evidence from zircon U-Pb chronology, mineralogy and geochemistry[J],2023,39(5).
APA	Guan Qi,Zhang MinJie,Cao JunLin,Shi HongJiang,Li ZengSheng,&Wang DuiXing.(2023).Late Cretaceous arc magma differentiation in southern Tibet: Evidence from zircon U-Pb chronology, mineralogy and geochemistry.ACTA PETROLOGICA SINICA,39(5).
MLA	Guan Qi,et al."Late Cretaceous arc magma differentiation in southern Tibet: Evidence from zircon U-Pb chronology, mineralogy and geochemistry".ACTA PETROLOGICA SINICA 39.5(2023).