Metamorphic Age Comparison and Its Implications between the Zuoquan and Zanhuang Complexes in the Central North China Craton, Based on LA-ICP-MS Zircon U–Pb Dating

Abstract

The Trans-North China Orogen (TNCO) is well-known as an early Precambrian orogenic belt in the North China Craton (NCC). Three meaningful groups of metamorphic ages have been reported in the metamorphic complexes throughout the TNCO, including c. 1.85 Ga, c. 1.95 Ga, and c. 2.5 Ga. The spatial distributions and relationships of these ages provide notable insight into the formation timing and tectonic evolution of the NCC basement. The Zuoquan and Zanhuang complexes are exposed in the south–central TNCO and are adjacent to the Eastern Block. In order to place new constraints on the timing of two phases of metamorphism that occurred in the complexes, combined U–Pb and rare earth element analyses were performed on zircons from different types of metamorphic rocks. Uranium–Pb zircon dating in this study shows that two groups of metamorphic ages of 1.88–1.85 Ga and 2.48–2.46 Ga were commonly recorded by metamorphic rocks in the Zanhuang and Zuoquan complexes, respectively. Our previous geochronological studies showed that metamorphic ages of c. 2.51 Ga and c. 1.90 Ga were locally recorded in the Zanhuang and Zuoquan complexes, respectively. These data indicate that metamorphic rocks in the two complexes underwent at least two phases of metamorphism, i.e., 2.51–2.46 Ga (Phase I) and 1.90–1.85 Ga (Phase II). In combination with previous studies regarding reaction microstructures, metamorphic pressure–temperature paths, and geochronology, the Phase II metamorphic ages are interpreted to be linked to the collision between the Western and Eastern Blocks along the TNCO between 1.97 Ga and 1.80 Ga, whereas the Phase I metamorphic ages, as a result of an earlier and extensive tectono-thermal event that occurred in the Eastern and Western Blocks of the NCC, were related to underplating of mantle-derived magma. It is inferred that the rocks with c. 2.51–2.46 Ga metamorphic ages in the two complexes formed in the Eastern Block and underwent regional metamorphism during that period, and then were tectonically involved in the TNCO and experienced c. 1.90–1.85 Ga metamorphism. Metamorphic peaks occurred at different crustal levels in the orogen, resulting in distinct metamorphic ages and peak conditions preserved by metamorphic rocks in the two complexes.

Passive margins in accreting Archaean archipelagos signal continental stability promoting early atmospheric oxygen rise

“…Widespread anatexis and intense reworking of the basement makes the formation ages difficult to extract. There is a paucity of previously reported ages of the Archaean rocks in the basement igneous complex, limited to a few metamorphic age reports of 2.51–2.46 Ga 27 , 28 , constraining that the basement formation predates this metamorphism. Our study constrains the anatectic event from monzogranite to be 2489 ± 6 Ma (Supplementary Fig.…”

Two Paleoproterozoic tectono‐thermal events in the Central Orogenic belt, North China craton, determined from EPMA Th–U–Pb monazite geochronology of the Zanhuang massif

“…Li et al (2016) reported an 1882 ± 15 Ma zircon U–Pb age for the Eastern Zanhuang domain diorite. Xiao & Chen (2019) reported ca. 1875–1858 Ma zircon U–Pb ages for metapelites of the central and southern of the Eastern Zanhuang domain, which are interpreted to be peak metamorphic ages.…”

New Insights into Pre-to-Post Ediacaran Zircon Fingerprinting of the Mamfe PanAfrican Basement, SW Cameroon: A Possible Link with Rocks in SE Nigeria and the Borborema Province of NE Brazil

“…Another Mid Neoproterozoic age ( 206 Pb/ 238 U 740 Ma and 207 Pb/ 235 U 685 Ma) was obtained in zircon (24) (spot AR2-7-R). This zircon's U (134.2 ppm), Th (289.8 ppm), and Th/U (2.16 ppm) are within the range limit of crustal magmatic zircons[5,6,19,23], and therefore show crystallization of a crustal magma, different to that of the Cryogenian metamorphic recrystallization zone (AR2-5R2) found in zircon(14). Consequently, the 740 to 685 Ma zircon could be an inherited grain.LateNeoproterozoic ( 206 Pb/ 238 U 544-616 Ma and 207 Pb/ 235 U 547-618 Ma) ages obtained in part of the studied zircons show that they registered Ediacaran events of three different periods (Early Ediacaran 605-617 Ma, Mid Ediacaran 571-579 Ma, and Late Ediacaran 498-554 Ma).…”

“…Zircon geochronology is one of the key methods used to determine the ages of geological processes, including magmatic crystallization, different post-crystallization episodes [1][2][3][4][5][6][7], fingerprinted metamorphism [2,[8][9][10][11][12][13][14], and hydrothermal activity [15][16][17][18]. It also helps for provenance studies and paleogeographic reconstitution (e.g., [19][20][21][22][23][24][25][26][27][28][29]).…”