皖南绩溪县靠背尖高Ba-Sr花岗闪长斑岩年代学及其成因

Translated title of the contribution: Petrogenesis and geochronology of the high Ba-Sr Kaobeijian granodiorite porphyry, Jixi County, South Anhui Province

Xiang Zhou*, Xinqi Yu, Heming Yang, Deen Wang, Yudiao Du, Hongbiao Ke

*Corresponding author for this work

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

The Kaobeijian granodiorite porphyry, outcrop area of 0.7km2, is a small stock which intruded into Neoproterozoic-Paleozoic marine sedimentary strata in Jixi County, South Anhui Province. With hornblende grains, this porphyry are composed of SiO2 64. 05% ∼69. 64% and total alkalis (K2O + Na2O) 6. 1% ∼11. 5%, with A/CNK values 0. 77 ∼0. 98. Their LREE/HREE ratios are high and Eu is a bit depleted. It belongs to I-type granitoid formed in an island-arc environment. The Kaobeijian granodiorite porphyry have εNd(t) values of -3. 69 ∼ -6. 24 and initial 87Sr/86Sr ratios of 0. 70784 ∼0. 71033, roughly in conformity to the syntectic type granites of southern China. The unusual high Ba-Sr composition comes from Neoproterozoic granodiorites which was enriched of Ba-Sr. The mantle-derived materials likely played an important role in the generation of the magma, letting the S-type magma gradually transformed into I-type magma in mixing process. In addition, lots of felsic-quartz veins and hydrothermal alteration indicate that the stock had been underwent an intensively residual melting and/or hydrothermal fluid activities. And the quartz of granodiorite were transformed into sub-grains under high temperature. All these indicate that pervious 40Ar/39Ar age of 134. 3 ± 1.4 Ma for biotite from the Kaobeijian granodiorite porphyry is more likely to document a tectonic-thermal event, rather than the forming age of the rock. SHRIMP zircon U-Pb analyses yield consistent ages of 151. 9 ± 1. IMa, 152. 9 ± 1. IMa and 147. 7 ± 1. 3Ma for three samples of granodiorite, indicate the magma was emplaced in Late Jurassic.

Original languageChinese
Pages (from-to)3403-3417
Number of pages15
JournalActa Petrologica Sinica
Volume28
Issue number10
Publication statusPublished - 2012
Externally publishedYes

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Keywords

  • High Ba-Sr
  • Kaobeijian granodiorite porphyry
  • Petrogenesis
  • SHRIMP zircon U-Pb dating
  • South Anhui

Cite this

Zhou, X., Yu, X., Yang, H., Wang, D., Du, Y., & Ke, H. (2012). 皖南绩溪县靠背尖高Ba-Sr花岗闪长斑岩年代学及其成因. Acta Petrologica Sinica, 28(10), 3403-3417.