LA-ICPMS zircon U-Pb geochronological constraints on the tectonothermal evolution of the Early Paleoproterozoic Dakendaban Group in the Quanji Block, NW China

• 来源期刊: 科学通报(英文版)
• 年，卷（期）: 2008,（18）
• 页码范围: 2849-2858
• 页数: 10页
• 语种: 英文
• DOI: 10.1007/s11434-008-0265-x

摘要

The Ouanji Block, situated between the northern margin of the Oaidam Block and the South Qilian orogenic belt in the NE Qinghai-Tibet Plateau, China, is thought to represent a remnant continental crust. In this study, LA-ICPMS U-Pb analyses of detrital zircon grains from two mesosomes in the migmatitic Dakendaban Group yield ages of 2467+281-26 Ma and 2474+66/-52 Ms, respectively. Zircon grains from a leucosome give two distinct ages of 2471+18/-16 Ma and 1924+14/-15 Ms. Zircon from a granitic pegmatite that intruded into the Dakendaban Group yields an age of 2427+44/-38 Ms. These data suggest that the Early Paleoproterozoic Dakendaban Group deposited between ～2.43 to ～2.47 Ga and has been subject to an intrusive event at 2.43 Ga, and regional metamorphism-anatexis at 1.92 Ga. The common lower intercept age of ～0.9 Ga probably records a significant Early Neoproterozoic event in the Quanji Block.