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Zhang J.-F.,Geological Survey Institute of Zhejiang Province | Xie H.-S.,Geological Survey Institute of Zhejiang Province | Xu X.-M.,Geological Survey Institute of Zhejiang Province | Gong R.-J.,Geological Survey Institute of Zhejiang Province
Geology in China | Year: 2013

Located in the northeastern part of the Qinhang metallogenic belt, Lizhu area in Zhejiang has developed a series of skarn type iron polymetallic deposits or ore spots, and mineralization is closely related to the late Jurassic intrusive rocks in the NE-trending fold-fault zone. Researches on the geological and geochemical characteristics of intrusive rocks show that the main rock types are middle-fine grained granodiorite and coarsegrained or fine-grained granite. The former type comprises amphibole-bearing calc-alkaline ( low potassium-high calcium) granitoids (ACG) characterized by low Si02, K20+Na20 and K20/Na20, rich CaO, MgO and FeOT, relative enrichment of K, Rb, Ba, Th, U, Zr, Hf, slight depletion of Sr, Ti, negative Eu anomalies along REE distribution curve with weakly right-oblique nature, similar geochemically to the I-type granite. The latter type consists of alkali-rich calc-alkaline (high potassium-low calcium) granitoids (KCG), characterized by high Si02)K20+Na20 and K20/Na20, low CaO, MgO and FeOT, enrichment of K, Rb, Th, U, Nb, Ta, Zr, Hf, strong depletion of Ba, Sr, Ti, and obvious negative Eu and "V"-type REE patterns, thus similar geochemically to the A-type granites. The petrogenetic tectonic environment was converted from the subduction collision to post-collision or post-orogeny, consistent with the conversion of the tectonic environment in South China, thus providing a new constraint for the tectonic-magmatic evolution in South China. Furthermore, both the two types of granites widespread in Zhejiang have good prospecting potential.

Wang J.-G.,Geological Survey Institute of Zhejiang Province | Yu S.-Q.,Geological Survey Institute of Zhejiang Province | Hu Y.-H.,Geological Survey Institute of Zhejiang Province | Zhao X.-D.,Geological Survey Institute of Zhejiang Province | And 2 more authors.
Geology in China | Year: 2014

This paper reports retrograde eclogite that occurs in lanticular form in Xikou area of Jiangshan-Shaoxing suture zone. The retrograde eclogite consists of the mineral assemblage of amphibole+garnet+clinopyroxene+plagioclase+quartz. A clear 'whiteeye' structure is well developed, garnet is rimmed with symplectitic plagioclase, and clinopyroxene is surrounded by symplektic plagioclase and amphibole. Zircon U-Pb dating by LA-ICP-MS shows that the peak metamorphic age is (451+8/-18)Ma. Exposures of retrograde eclogites in the Jiangshan-Shaoxing suture zone provide new insight for the collisional process between the Cathaysia block and the Yangtze block.

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