Breeding habitat selection by houbara bustard<Emphasis Type="Italic">(Chlamydotis [undulata] macqueenii</Emphasis>) in Mori,Xinjiang, China |
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Authors: | Weikang Yang Jianfang Qiao Olivier Combreau Jun Yao Xingyi Gao Wenqin Zhong |
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Institution: | (1) Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640 Guangzhou, China |
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Abstract: | The protoliths of mafic-ultramafic plutons in the northern Dabie Mts. (NDM) (Hubei) include pyroxenite and gabbro. The zircon
U-Pb dating for a gabbro suggests that emplacement of mafic magma took place in the post-collisional setting at the age of
122.9±0.6 Ma. It is difficult to obtain a reliable Sm-Nd isochron age, due to disequilibrium of the Sm-Nd isotopic system.
Two hornblende40Ar/39Ar ages of 116.1±1.1 Ma and 106.6±0.8 Ma may record cooling of metamorphism in the mafic-ultramafic plutons in Hubei below
500°C. The hornblende40Ar/39Ar ages for the mafic-ultramafic rocks in Hubei are evidently 15–25 Ma younger than those for the same rocks in Anhui, indicating
that there is a diversity of the cooling rates for the mafic-ultramafic rocks in Hubei and Anhui. The difference in their
cooling rates may be controlled by the north-dipping normal faults in the NDM. The intense metamorphism occurring in the mafic-ultramafic
rocks in Hubei may result from the Yanshanian magmatic reheating and thermal fluid action induced by the Cretaceous migmatization.
The geochemical similarity of these mafic-ultramafic rocks wherever in Hubei and Anhui may be attributed to the same tectonic
setting via an identical genetic mechanism. |
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Keywords: | mafic-ultramafic plutons geochronology Dabie Mountains |
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