Morphology, trace elements, and geochronology of zircons from monzogranite in the Northeast Xing'an Block, northeastern China: constraints on the genesis of the host magma |
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The morphology, trace-element composition and geochronology of 43 zircon grains from two monzogranite samples from the Northeast Xing'an Block, northeastern China, were determined using cathodoluminescence imaging and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Three morphological subtypes (S3, S8 and S9) are recognized in the zircon grain samples, and subtype S8 is dominant, reflecting a calc-alkaline, moderately aluminous, high-pressure crystallization medium and a crystallization temperature of 700 +/- 50 degrees C. The zircon grains are characterized by oscillatory zoning, relatively high Th/U ratios (0.3-1.0), steep chondrite-normalized rare-earth element patterns, high Hf contents (>9000 ppm), positive Ce (Ce/Ce* = 4.84 to 2914) and negative Eu (Eu/Eu* = 0.24 to 0.90) anomalies, indicating a magmatic source. The Pb-206/U-238 ages of the two monzogranite samples are 180 +/- 1 and 181 +/- 1 Ma, respectively, implying an Early Jurassic emplacement age for the intrusion. The disparate geochemical behaviors of Hf, Th, and Nb within the zircons, as well as the U/Yb, Nb/Yb, Th/U, Nb/Hf, Th/Nb, and Hf/Th ratios, suggest a continental-crust source in a compressional-magmatic-arc or orogenic-tectonic setting, and a calc-alkaline parent magma. All of the grains show relatively high Ce4+/Ce3+ ratios, suggesting that they were derived from an oxidized magma, which favors enrichment of Cu-Mo elements in the granite porphyry. Publication name | MINERALOGY AND PETROLOGY, 113 (5):651-666; 10.1007/s00710-019-00669-9 OCT 2019 | Author(s) | Deng, Changzhou; Sun, Guangyi; Sun, Deyou; Han, Jinsheng; Yang, Dongguang; Tang, Zongyuan | Corresponding author(s) | SUN Deyou sundy@jlu.edu.cn Jilin Univ, Coll Earth Sci, Changchun 130061, Jilin, Peoples R China Minist Land & Resources, Key Lab Mineral Resources Evaluat Northeast Asia, Changchun 130061, Jilin, Peoples R China | Author(s) from IGCAS | SUN Guangyi | View here for the details
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