U-Pb zircon LA-ICP-MS and Hf composition in granitogneiss of Chu Lai body and its implication of the Kontum massif, central Vietnam
- Authors: Trong Huu Nguyen 1*, Dung Tien Le 1, Ban Xuan To 1, Anh Van Thi Pham 1, Thanh Xuan Ngo 1, Nhu Thanh Ha 1, Ly Ly Thi Nguyen 2
1 Hanoi University of Mining and Geology, Hanoi, Vietnam
2 Vietnam Insitutute of Geosciences and Mineral Resources, Hanoi, Vietnam
- Received: 16th-Oct-2021
- Revised: 23rd-Jan-2022
- Accepted: 21st-Mar-2022
- Online: 31st-Aug-2022
- Section: Geology - Mineral
The Chu Lai granitogneiss is widespread throught the Northern Kontum massif. The Chu Lai body is located in the W-SW of the Nui Thanh Townlet (Nui Thanh Dists., Quang Nam Prov.). On an areas of ~ 300 km2. The Chu Lai intrusion mainly consists two mica gneiss, it is light grey and have porphyritic textures. Its major minerals include plagioclase (25÷40%), K-feldpar (20÷40%), quartz (25÷35%), biotite (5÷13%) and mustcovite (0÷6%). Accessory minerals are apatite, zircon, orthit. Garnet and tourmaline are occiasionally found. Zircons separated from a granitogneiss sample colleted in Chu Lai body are generally euhedral to subhedral, dark gray and prissmatic in shape with 100÷300 µm, with length/witdth ratios from 1:1÷1:3. There are many Neoproterozoic - Cambrian ages among the zircon cores in the Chu Lai samples, and these are regarded as inherited zircons. The LA-ICP-MS zircon age is 431 Ma, corresponding to the Silurian. The Chu Lai granitogneiss strongly negative zircon εHf (-4.2÷-11.4) and complex inherited zircon components, characteristics of typical S-type granite. Hf model ages TDM2 1.5÷1.9 Ga, suggests that the Chu Lai granitogneiss was derived from partial melting of old crustal basement rocks, probaly Paleoproterozoic in age.
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