Petrogenesis and Geotectonic Significance of Early-Neoproterzoic Olivine-Gabbro within the Yangtze Craton： Constrains from the Mineral Composition, U-Pb Age and Hf Isotopes of Zircons

The olivine-gabbroic rocks located at the Huangiing anticline within the Yangtze Craton are dated at circa 857-854 Ma by LA-ICP-MS method. The rocks belong to the sub-alkaline series and consist of pyroxene （35%-40%）, plagioclase （40% -45%）, olivine （8%-10%） and spinel （3%-5%）. Olivine has Fo values...

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Bibliographic Details
Published in:Journal of earth science (Wuhan, China) China), 2018-02, Vol.29 (1), p.93-102
Main Authors: Jiang, Xingfu, Peng, Songbai, Kusky, Timothy M., Wang, Lu, Deng, Hao
Format: Article
Language:English
Subjects:
Aluminum oxide
Anticlines
Biogeosciences
Cratons
Earth and Environmental Science
Earth Sciences
Gabbro
Geochemistry
Geochronometry
Geology
Geotechnical Engineering & Applied Earth Sciences
Isotopes
Magma
Mantle
Mineral composition
Mineralogy and Petrogeochemistry
Minerals
Olivine
Orogeny
Petrogenesis
Plagioclase
Plate tectonics
Pyroxenes
Radiometric dating
Rock
Rocks
Spinel
Uranium
Zircon
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Summary:The olivine-gabbroic rocks located at the Huangiing anticline within the Yangtze Craton are dated at circa 857-854 Ma by LA-ICP-MS method. The rocks belong to the sub-alkaline series and consist of pyroxene （35%-40%）, plagioclase （40% -45%）, olivine （8%-10%） and spinel （3%-5%）. Olivine has Fo values of 73-83 that is classified as chrysolite. Pyroxene has relative low contents of FeO （6.60 wt.%-8.23 wt.%） but high CaO （20.23 wt.%-21.25 wt.%） contents, however, plagioclase has high A1203 （31.78 wt.%o-32.37 wt.%）, CaO （16.08 wt.%-16.25 wt.%） and An （79-80） values, but low Na20 contents （1.95 wt.%-2.11 wt.%）. Spinel are magnesioferrite with characteristics of high contents of MgO （13.65 wt.%- 13.68 wt.%）, FeO （23.27 wt.%-23.40 wt.%） and A1203 （62.43 wt.%-62.74 wt.%）. Chemical compositions of these minerals are similar to those of gabbro rocks that were formed in the post-orogeny environment. The olivine-gabbro samples have negative zircon eHf values （-16.57±0.47） that resemble the mafic rocks in the same region, indicating that they are derived from the extremely enriched mantle source. On the compilation of documented Neoproterozoic mafic rocks in the Yangtze Craton, it is proposed that the mantle in the northern Yangtze Craton has experienced different degrees enrichment during the Neoproterozoic.
ISSN:1674-487X
1867-111X
DOI:10.1007/s12583-018-0821-5