期刊
INTERNATIONAL GEOLOGY REVIEW
卷 53, 期 1, 页码 61-83出版社
TAYLOR & FRANCIS INC
DOI: 10.1080/00206810902900319
关键词
intrusive complexes; foundering; underplating; Sulu belt; eastern China
类别
资金
- Knowledge innovation project [KZCX2-YW-111-03]
- National Nature Science Foundation of China [40673029, 40773020, 90714010, 40634020]
TPost-orogenic intrusive complexes from the Sulu belt of eastern China consist of pyroxene monzonites and dioritic porphyrites. We report new U-Pb zircon ages, geochemical data, and Sr-Nd-Pb isotopic data for these rocks. Laser ablation-inductively coupled plasma-mass spectrometry U-Pb zircon analyses yielded a weighted mean 206Pb/238U age of 127.4 +/- 1.2Ma for dioritic porphyrites, consistent with crystallization ages (126Ma) of the associated pyroxene monzonites. The intrusive complexes are characterized by enrichment in light rare earth elements and large ion lithophile elements (i.e. Rb, Ba, Pb, and Th) and depletion in heavy rare earth elements and high field strength elements (i.e. Nb, Ta, P, and Ti), high (87Sr/86Sr)i ranging from 0.7083 to 0.7093, low epsilon Nd(t) values from epsilon 14.6 to -19.2, 206Pb/204Pb=16.65-17.18, 207Pb/204Pb=15.33-15.54, and 208Pb/204Pb=36.83-38.29. Results suggest that these intermediate plutons were derived from different sources. The primary magma-derived pyroxene monzonites resulted from partial melting of enriched mantle hybridized by melts of foundered lower crustal eclogitic materials before magma generation. In contrast, the parental magma of the dioritic porphyrites was derived from partial melting of mafic lower crust beneath the Wulian region induced by the underplating of basaltic magmas. The intrusive complexes may have been generated by subsequent fractionation of clinopyroxene, potassium feldspar, plagioclase, biotite, hornblende, ilmenite, and rutile. Neither was affected by crustal contamination. Combined with previous studies, these findings provide evidence that a Neoproterozoic batholith lies beneath the Wulian region.
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