NDLI: Possible early Neoproterozoic magmatism associated with slab window in the Pingshui segment of the Jiangshan-Shaoxing suture zone: Evidence from zircon LA-ICP-MS U-Pb geochronology and geochemistry

Content Provider	Springer Nature Link
Author	Chen, ZhiHong Guo, KunYi Dong, YongGuan Chen, Rong Li, LongMing Liang, YiHong Li, ChunHai Yu, XiMing Zhao, Ling Xing, GuangFu
Copyright Year	2009
Abstract	We report here geochemical data, U-Pb zircon ages, and Hf isotopes for the high-Mg diorites (HMDs), Nb-enriched basaltic porphyrys (NEBPs) and plagiogranites (PLAGs) in the Pingshui segment of the Jiangshan-Shaoxing suture zone. The HMDs are characterized by high Mg$^{#}$ (>60), high Na and LREE contents, depletion of HREE and HFSE, and pronounced positive ε$_{Nd}$(t) values of 7.0 to 7.7, similar to some adakitic high-Mg andesites. The NEBPs are relatively Na-rich (Na$_{2}$O/K$_{2}$O>6) and display high abundances of P$_{2}$O$_{5}$ (∼1.00%), TiO$_{2}$ (∼3.08%) and HFSE (e.g., Nb=9.53–10.27 ppm). Their Nd isotopic compositions (ε$_{Nd}$(t)=6.8–8.0) are comparable to those of the HMDs. The PLAGs are metaluminous (A/CNK=0.84–0.89) and sodic (Na$_{2}$O/K$_{2}$O>10). Their depletion in HFSE (e.g., Nb, Ta) is consistent with “SSZ-type” plagiogranite. Zircon LA-ICP-MS U-Pb dating yields an age of 932±7 Ma for the HMD, 916±6 Ma for the NEBP, and 902±5 Ma for the PLAG, respectively, indicating that they were products of early Neoproterozoic magmatism. The PLAGs exhibit relatively high zircon Hf isotopes and positive ε$_{Hf}$(t) values of 11.0 to 16.2, consistent with their Nd isotopic data (ε$_{Nd}$(t)=7.5–8.4). Such features are similar to those of oceanic plagiogranites in ophiolites and distinct from those of crust-derived granites. The PLAGs were most likely derived from partial melting of subducted oceanic crust in an active continental margin. Considering these results in the context of the regional geology, we suggest that a slab window in the subducting oceanic crust between the Yangtze Block and Cathaysia Block was possibly the principal cause for the unique arc magmatism in the area. The upwelling asthenosphere below the slab window may have provided significant thermodynamic conditions.
Starting Page	925
Ending Page	939
Page Count	15
File Format	PDF
ISSN	10069313
Journal	Science in China Series D: Earth Sciences
Volume Number	52
Issue Number	7
e-ISSN	18622801
Language	English
Publisher	SP Science in China Press
Publisher Date	2009-05-21
Publisher Place	Heidelberg
Access Restriction	Subscribed
Subject Keyword	zircon LA-ICP-MS U-Pb dating geochemistry slab window early Neoproterozoic Pingshui of Shaoxing Jiangshan-Shanxing suture zone Earth Sciences
Content Type	Text
Resource Type	Article
Subject	Earth and Planetary Sciences

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