Multiple thermal events recorded in the Acasta Gneiss Complex:Evidence from in-situ dating of zircon, titanite, and apatite  

作　　者：Qingfeng MEI Jinhui YANG Jinfeng SUN Qiuli LI Shitou WU Xiaoxiao LING Peng PENG Hao WANG 

机构地区：[1]State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [2]College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China [3]Key Laboratory of Computational Geodynamics,University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Science China Earth Sciences》2024年第3期673-686,共14页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China(Grants Nos.42103011,42073034;42288201);the B-type Strategic Priority Program of the Chinese Academy of Sciences(Grants No.XDB41000000)。

摘　　要：In-situ dating of the zircons, titanites, and apatites in the rock fragments of approximately 1 cm2in size from the Acasta Gneiss Complex was performed using secondary ion mass spectrometry or laser ablation inductively coupled plasma mass spectrometry to provide constraints on the thermal history of the Acasta Gneiss Complex. The zircons in these rock fragments typically exhibit multiple age populations, reflecting the presence of inherited zircons or the post-crystallization process of zircon overgrowth. Combined with previous studies, our zircon dating results reveal multiple magmatic events that occurred in the Acasta Gneiss Complex, specifically at >3.96, ~3.72, and ~3.57 Ga, respectively. A titanite Pb-Pb isochron age of2911±22 Ma(95% confidence level, MSWD=1.5) for sample AY199 is identified, consistent with the timing of the latest Archean magmatism in the Acasta Gneiss Complex. The titanite U-Pb ages for samples AC478 and AY066 are 1932±270 Ma(95% confidence level, MSWD=2.3) and 1813±45 Ma(95% confidence level, MSWD=2.3), respectively. The apatites in sample P090803-C exhibit a Pb-Pb isochron age of 1833±26 Ma(95% confidence level, MSWD=1.4). The apatite U-Pb ages for samples AC478, AY199, and AY066 are 1850±20 Ma(95% confidence level, MSWD=1.3), 1827±100 Ma(95% confidence level, MSWD=6.3), and 1807±58 Ma(95% confidence level, MSWD=3.9), respectively. Titanites in samples AC478 and AY066, as well as the apatites in all four investigated samples, show a uniform age(Pb-Pb or U-Pb age) of ~1.9–1.8 Ga,indicating U-Pb system reset in these minerals due to the Wopmay orogeny and documenting that the peak temperature condition associated with the Wopmay orogeny exceeded the apatite U-Pb closure temperature and approached or exceeded that of titanite.

关 键 词：ZIRCON TITANITE APATITE Acasta Gneiss Complex Wopmay Orogen 

分 类 号：P588.3[天文地球—岩石学] P597.3[天文地球—地质学]