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  4. 同位素地球化学国家重点实验室
Early Cretaceous fayalite-, ferrosilite-, and biotite-bearing rhyolitic porphyries in the Baishuizhai area, South China: Formation by fractional crystallization in the shallow crust

文献类型：期刊论文

作者Liu, Xiao3,4,5,6; Wang, Qiang3; Liu, Xi -Jun2,4,5,6; Ma, Lin3; Wyman, Derek A.1; Tang, Gong-Jian3; Dan, Wei3; Jiang, Zi-Qi6; Wu, Hao4,5,6; Hu, Wan -Long3
刊名LITHOS
出版日期2024-10-01
卷号482页码:19
关键词Fayalite and ferrosilite-bearing rhyolitic por phyry Biotite-bearing rhyolitic porphyry Flow differentiation Diachronous slab rollback Crust-mantle interaction
ISSN号0024-4937
DOI10.1016/j.lithos.2024.107694
英文摘要Fayalite- and ferrosilite-bearing felsic igneous rocks are a distinctive category of A-type granitic magmas, and the origins of these rocks have proved controversial. In addition, the shallow-crust high-silica rhyolitic magmas responsible for such rocks are considered to have higher viscosities than their plutonic equivalents, which casts doubt on whether fractional crystallization could have occurred during the evolution of these high-silica melts. Here, we report a study of earliest Early Cretaceous (145-142 Ma) fayalite- and ferrosilite-bearing rhyolitic porphyries (FFBRPs) and closely associated biotite-bearing rhyolitic porphyries (BBRPs) from the Baishuizhai area, Guangzhou, Guangdong Province, South China. The Baishuizhai suite provides an excellent opportunity to establish the magmatic origins and evolutionary processes responsible for the FFBRPs. Rocks from the Baishuizhai suite have SiO2 contents of 73.2-77.7 wt%, Na2O + K2O contents of 7.83-9.42 wt%, and Fe2O3T contents of 1.52-2.97 wt%. They have A-type granite features including mineral assemblages (euhedral fayalite and ferrosilite in addition to anhedral amphibole and biotite) and geochemical characteristics [e.g., high 10,000 x Ga/Al values (3.7-4.7), high FeOT/MgO ratios (13.0-34.8), and high Zr (245-514 ppm) and Nb (56.4-96.5 ppm) contents]. The rocks have slightly enriched in situ plagioclase Sr [(Sr-87/Sr-86)(i) = 0.7070-0.7076] and whole-rock Nd [epsilon(Nd)(t) = -2.3 to -2.0] compositions and depleted zircon Hf isotopic compositions [epsilon(Hf)(t) = -0.9 to +7.0] relative to chondrite, as well as higher zircon delta O-18 values (6.3 parts per thousand-7.8 parts per thousand) and intermediate in situ plagioclase Pb isotopic compositions [(Pb-206/Pb-204)(i) = 18.368-18.727, (Pb-207/Pb-204)(i) = 15.488-15.673, and (Pb-208/Pb-204)(i) = 38.049-38.801] compared with depleted mantle. We infer that the primary magmas of this rock suite were formed by mixing of mantle-derived magmas with subordinate (20%-50%) metasedimentary-rock-derived magmas. Fayalite and ferrosilite in the FFBRPs were most likely crystallized from dry, hot, and reduced magma in a lower (<16.5 km depth) chamber. The lower magma gradually evolved during ascent to a water-enriched magma in an intermediate chamber at a shallow depth (3-4 km), forming the FFBRPs (elevation: 129-168 m). Finally, the residual melts migrated upward and resided in an upper (<3 km depth) chamber, forming the BBRPs (elevation: 196-824 m). According to the established temporal-spatial distribution of Early Cretaceous A-type granites and adakitic rocks in South China, we suggest that the Paleo-Pacific plate underwent diachronous rollback, starting during the earliest Early Cretaceous. This rollback enhanced the degree of crust-mantle interaction in the Guangzhou area.
WOS研究方向Geochemistry & Geophysics ; Mineralogy
语种英语
WOS记录号WOS:001261272000001
源URL[http://ir.gig.ac.cn/handle/344008/78252]  
专题同位素地球化学国家重点实验室
通讯作者Wang, Qiang
作者单位1.Univ Sydney, Sch Geosci, Camperdown, NSW 2006, Australia
2.Chinese Acad Sci, Xinjiang Inst Ecol & Geog, Xinjiang Res Ctr Mineral Resources, Urumqi 830011, Peoples R China
3.Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Isotope Geochem, Guangzhou 510640, Peoples R China
4.Guilin Univ Technol, Guangxi Sci Innovat Base Format & Explorat Strateg, Guilin 541006, Peoples R China
5.Guilin Univ Technol, Collaborat Innovat Ctr Explorat Nonferrous Met Dep, Guilin 541006, Peoples R China
6.Guilin Univ Technol, Coll Earth Sci, Guangxi Key Lab Hidden Met Ore Deposits Explorat, Guilin 541006, Peoples R China
推荐引用方式
GB/T 7714		 Liu, Xiao,Wang, Qiang,Liu, Xi -Jun,et al. Early Cretaceous fayalite-, ferrosilite-, and biotite-bearing rhyolitic porphyries in the Baishuizhai area, South China: Formation by fractional crystallization in the shallow crust[J]. LITHOS,2024,482:19.
APA Liu, Xiao.,Wang, Qiang.,Liu, Xi -Jun.,Ma, Lin.,Wyman, Derek A..,...&Fang, Gui-Cong.(2024).Early Cretaceous fayalite-, ferrosilite-, and biotite-bearing rhyolitic porphyries in the Baishuizhai area, South China: Formation by fractional crystallization in the shallow crust.LITHOS,482,19.
MLA Liu, Xiao,et al."Early Cretaceous fayalite-, ferrosilite-, and biotite-bearing rhyolitic porphyries in the Baishuizhai area, South China: Formation by fractional crystallization in the shallow crust".LITHOS 482(2024):19.

入库方式： OAI收割

来源：广州地球化学研究所

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