Neoproterozoic Crustal Reworking and Growth in the Zhangbaling Uplift, Tan–Lu Fault Zone: Evidence from the Feidong Complex and Zhangbaling Group

Abstract

Intensive mid‐Neoproterozoic magmatism is the salient feature of the Yangtze Block, preserving abundant information about crustal reworking and growth. Zircon U–Pb–Lu–Hf isotope analysis was performed on material from the Feidong Complex (FDC) and Zhangbaling Group (ZBLG) of the Zhangbaling Uplift, in order to determine the age and magmatic source of the Neoproterozoic igneous rocks as well as the detrital provenance for the sedimentary rocks, to further provide important data for understanding the mid‐Neoproterozoic crustal evolution of the Northeast Yangtze Block. The amphibolite and gneissic granites in the Feidong Complex (FDC) gave similar protolith ages of 782–776 Ma. The synmagmatic zircons exhibited variable negative ∊Hf(t) values of –26.9 to –8.3. Early (ca. 2.4 Ga) to late Paleoproterozoic (ca. 2.0–1.9 Ga) inherited zircons were found in the gneissic monzogranite, with negative ∊Hf(t) values of –11.2 to –7.2, indicating strong reworking of the ancient crustal materials of the Northeast Yangtze Block. Whereas the amphibolites represent minor crustal growth through emplacement of continental rifting‐related mafic magmas. The quartz–keratophyres in the Xileng Formation of the ZBLG in contrast systematically yield young protolith crystallization ages of 754–727 Ma with high ∊Hf(t) values of –2.0 to +5.6, indicating their derivation from the reworking of juvenile crustal materials. The detrital zircons from the metasiltstone in the Beijiangjun Formation yield variable 206Pb/238U ages (871–644 Ma) with a peak age at 741 ± 11 Ma and ∊Hf(t) values of –4.3 to +5.3, which is consistent with those of the Xileng Formation, but distinct from the FDC, indicating that the provenance of the metasiltstone is primarily the underlying Xileng Formation. The mid‐Neoproterozoic igneous and sedimentary rocks of the Zhangbaling Uplift were products from continental rifting zones along the northern margin of the Yangtze Block, situated in different positions from the Susong Complex and the Haizhou Group. The transition from ancient to juvenile crustal sources for felsic magmatic rocks is attributed to gradually increased crustal extension during continental rifting.

Tectonic affinity and geological significance of the Feidong Complex in the northeastern margin of the Yangtze Craton: Evidence from zircon U–Pb and Lu–Hf isotopes of the basement rocks

“…Over the last few decades, research on the Feidong Complex has mainly focused on Neoproterozoic magmatism and Mesozoic tectonic evolution (Cai et al, 2021;Li et al, 2020;Liu et al, 2015;Niu et al, 2020;Zhu et al, 2018). However, research on early basement rocks is limited, despite the significant role of their formation age in Moreover, recent research has identified large volumes of Neoproterozoic magmatic rocks with ages of 823-745 Ma within the Feidong Complex (Cai et al, 2021;Liu et al, 2015).…”

Continent‐Continent Collision Between the South and North China Plates Revealed by Seismic Refraction and Reflection at the Southern Segment of the Tanlu Fault Zone

“…Thus, the TFZ could act as a conducting channel for the upwelled asthenosphere materials. That is, the collision and subduction between the NCP and SCP at the DOB and SOB first begun with the oceanic subduction before switching to the continent-continent type (Niu et al, 2020); later during the intra-continental collision, the deep mantle and/or recycled crustal material from the asthenospheric upwelling in the Mesozoic regional magmatism was injected into the crust through the previously formed shearing zone in the Zhangbaling area (Lü et al, 2013(Lü et al, , 2015Shi et al, 2013).…”

Dating Strike‐Slip Ductile Shear Through Combined Zircon‐, Titanite‐ and Apatite U–Pb Geochronology Along the Southern Tan‐Lu Fault Zone, East China

“…Further geochronological information can be extracted from Early Cretaceous granites and granitic veins that intrude or crosscut the shear zone and have been dated between ca. 134 and 103 Ma (Niu et al., 2008; Zhu et al., 2010, 2018), which indicates the shear zone formed before 134 Ma.…”

“…The Feidong complex consists mainly of plagioclase amphibolite, biotite‐plagioclase gneiss and hornblende‐plagioclase gneiss, with 2.6 and 2.0 Ga protoliths (Y. Shi et al., 2016; Tong & Xu, 2000; Tu et al., 2021; Ye et al., 2017; Q. Zhang et al., 2007) unconformably overlain by Middle‐Late Proterozoic phosphorous limestones (J. Xu et al., 1987, W. Xu et al., 2002; Q. Zhang et al., 2007). This rock package was intruded by bimodal magmas during the Neoproterozoic era (810 and 740 Ma) (Kang et al., 2013; L. Liu et al., 2015; Niu et al., 2020; Zhao et al., 2014). The Feidong complex records amphibolite‐facies metamorphism but the timing of peak metamorphism remains controversial and is variously suggested to be: (a) ∼688 Ma (Ge & Zhou, 1993), (b) 242 ± 26 Ma (Zhao et al., 2014), or (c) 167–133 Ma (Y. Shi et al., 2016).…”

“…This rock package was intruded by bimodal magmas during the Neoproterozoic era (810 and 740 Ma) (Kang et al, 2013;L. Liu et al, 2015;Niu et al, 2020;Zhao et al, 2014). The Feidong complex records amphibolite-facies metamorphism but the timing of peak metamorphism remains controversial and is variously suggested to be: (a) ∼688 Ma (Ge & Zhou, 1993), (b) 242 ± 26 Ma (Zhao et al, 2014), or (c) 167-133 Ma (Y.…”