Source characteristics of Late Neoarchean diatexite in the Yishan area, western Shandong

Authors：Li Yuan; Xie HangQiang; Dong ChunYan; Wang ShiJin; Wan YuSheng^*

Source：ACTA PETROLOGICA SINICA, 2022, 38(3): 598-618.

DOI：10.18654/1000-0569/2022.03.02

• Enclave
• Diatexite
• Source component
• Neoarchean
• Western Shandong Province

There are abundant enclaves of different ages and types within diatexite in the Yishan area, western Shandong. Based on field work, this paper carried out zircon SHRIMP U-Pb dating and Hf isotope analysis and whole-rock geochemical studies on enclaves in the diatexite. A tonalitic gneiss enclave has a formation age of similar to 2. 7Ga. Two episodes of Neoarchean mafic magmatism are recognized at 2. 69Ga and 2. 53 similar to 2. 51Ga, respectively, and they have metamorphic ages of 2. 52 similar to 2. 50Ga. Hornblende-plagioclase gneiss was interbedded with fine-grained biotite-hornblende gneiss, and these two types of gneisses are considered to be meta-volcanic rocks. The hornblende-plagioclase gneiss has a magmatic zircon age of 2. 51Ga. The magmatic zircon from the meta-gabbro has epsilon(Hf) ( t) values of 0 similar to + 8. 1 with t(DM1), of 2. 83 similar to 2. 54 Ga, whereas the magmatic zircon from the hornblende-plagioclase gneiss has epsilon(Hf) (t) values of -1. 2 similar to +5. 8 with t(DM1) of 2. 89 similar to 2. 71Ga. Combined with previous work, it is speculated that the source of the diatexite includes Early Neoarchean tonalitic gneiss and meta-gabbro, and Late Neoarchean quartz diorite gneiss, meta-volcanic rock and amphibolite. similar to 2. 5Ga mafic magmatism is widely developed in western Shandong, which provides the heat source for the Late Neoarchean anataxis, resulting in the formation of diatexite and crustally-derived granite.