Widespread Archean basement beneath the Yangtze craton

Abstract

The age distribution of the crust is a fundamental parameter in modeling continental evolution and the rate of crustal accretion through Earth's history, but this is usually estimated from surface exposures. The exposed Yangtze craton in eastern China consists mainly of Proterozoic rocks with rare Archean outcrops. However, the U-Pb ages and Hf isotope systematics of xenocrystic zircons brought to the surface in lamproite diatremes from three Proterozoic outcrop areas of the craton suggest the widespread presence of unexposed Archean basement, with zircon age populations of 2900-2800 Ma and 2600-2500 Ma and Hf model ages of 2.6 to ca. 3.5 Ga or older. The zircons also record thermal events reworked on the craton ca. 2020 Ma (remelting of older crust) and 1000-850 Ma (addition of juvenile mantle material). The observation of deep crust significantly older than the upper crust will require revision of models for the rates of crustal generation through time.

Late Miocene provenance change on the eastern margin of the Yinggehai-Song Hong Basin, South China Sea: Evidence from U–Pb dating and Hf isotope analyses of detrital zircons

“…The basement rocks of the southern Yangtze Block are of Proterozoic and Archean age (2100e1700 Ma and 2800e2300 Ma, respectively) (Metcalfe, 2006;Zheng et al, 2006). The block is characterized by Neoproterozoic magmatic activity (1000e700 Ma) (Chen and Jahn, 1998;, probably in response to the breakup of Rodinia Ling et al, 2003).…”

Zircon U-Pb geochronology and heavy mineral composition constraints on the provenance of the middle Miocene deep-water reservoir sedimentary rocks in the Yinggehai-Song Hong Basin, South China Sea

“…The Yangtze Block is separated from the North China Craton by the Qinling-Dabie orogenic belt to the north and is bounded on the west and south by the Tibetan Plateau and Indochina Block, respectively. Archean and Proterozoic basement rocks have been recognized in southern Yangtze Block with zircon U-Pb ages at 2800e2300 Ma and 1700e2100 Ma (Qiu et al, 2000;Metcalfe, 2006;Zheng et al, 2006). Neoproterozoic magmatism (1000e700 Ma), including granites, volcanic rocks and ophiolites, occurred sporadically around the Yangtze Block (Li, 1999;Zhou et al, 2002Zhou et al, , 2006Xiao et al, 2007;Ye et al, 2007), which probably produced by the pre-breakup of Rodinia and subsequent migration of South China (Zhou et al, 2002;.…”

Discovery of Paleoproterozoic rapakivi granite on the northern margin of the Yangtze block and its geological significance

“…In addition, researchers have obtained ca. 2000 Ma zircon xenocryst ages (using LA-ICPMS, the majority of zircons have Th/U>1) in the lamproite around the Yangtze block [30]. Furthermore, 2091-2025 Ma old zircon ages were measured in Mesozoic zircons of the Tongling district, Anhui Province (SHRIMP method, Th/U is 0.15-0.46, with oscillatory zoning) [76].…”

“…Kongling Complex) are rare in the Yangtze block [25][26][27][28]. Even so, recent studies have shown that there are chronological records of 1.8-2.1Ga tectonothermal events in the Yangtze block [29][30][31][32][33][34][35][36][37][38]. Some of these studies indicates that these events may be related to the amalgamation and breakup of the Columbia supercontinent [34][35][36][37][38].…”