Petrogenesis and Tectonic Setting of Early Cretaceous Intrusive Rocks in the Northern Ulanhot Area, Central and Southern Great Xing’an Range, NE China

Abstract

Abundant Early Cretaceous magmatism is conserved in the central and southern Great Xing’an Range (GXR) and has significant geodynamic implications for the study of the Late Mesozoic tectonic framework of northeast China. In this study, we provide new high-precision U–Pb zircon geochronology, whole-rock geochemistry, and zircon Hf isotopic data for representative intrusive rocks from the northern part of the Ulanhot area to illustrate the petrogenesis types and magma source of these rocks and evaluate the tectonic setting of the central-southern GXR. Laser ablation inductively coupled plasma–mass spectrometry (LA-ICP-MS) zircon U–Pb dating showed that magmatism in the Ulanhot area (monzonite porphyry: 128.07 ± 0.62 Ma, quartz monzonite porphyry: 127.47 ± 0.36, quartz porphyry: 124.85 ± 0.34, and granite porphyry: 124.15 ± 0.31 Ma) occurred during the Early Cretaceous. Geochemically, monzonite porphyry belongs to the metaluminous and alkaline series rocks and is characterized by high Al2O3 (average 17.74 wt.%) and TiO2 (average 0.88 wt.%) and low Ni (average 4.63 ppm), Cr (average 6.69 ppm), Mg# (average 31.11), Y (average 15.16 ppm), and Yb (average 1.62 ppm) content with enrichment in Ba, K, Pb, Sr, Zr, and Hf and depletion in Ti, Nb, and Ta. The granitic rocks (e.g., quartz monzonite porphyry, quartz porphyry, and granite porphyry) pertain to the category of high-K calc-alkaline rocks and are characterized by high SiO2 content (>66 wt.%) and low MgO (average 0.69 wt.%), Mg# (average 31.49 ppm), Ni (average 2.78 ppm), and Cr (average 8.10 ppm) content, showing an affinity to I-type granite accompanied by Nb, Ta, P, and Ti depletion and negative Eu anomalies (δEu = 0.57–0.96; average 0.82). The Hf isotopic data suggest that these rocks were the product of the partial melting of juvenile crustal rocks. Notably, fractionation crystallization plays a crucial role in the process of magma emplacement. Combining our study with published ones, we proposed that the Early Cretaceous intrusive rocks in the Ulanhot area were formed in an extensional tectonic background and compactly related to the subduction of the Paleo-Pacific Ocean plate.

Petrogenesis and tectonic implications of Early Cretaceous granite porphyry in the Taipingtun area, central Great Xing'an Range, NE China

“…The GXR has experienced multi‐stage tectono‐magmatism and recorded voluminous Late Mesozoic granitoid rocks (Figure 1c; Ge et al, 2005; Guo et al, 2020; S. Li et al, 2017; C. F. Liu et al, 2016; Lu et al, 2018; Song et al, 2015; Wei et al, 2020; J. H. Zhang et al, 2010; P. P. Zhu et al, 2016). In recent years, numerous geochronological studies have been conducted on these rocks (L. L. Chen & Cheng, 2015; F. Gao et al, 2018; Ge et al, 2005; Gu et al, 2015; Z. H. Li et al, 2020; C. F. Liu et al, 2016; Lu et al, 2018; Shi et al, 2013; Song et al, 2015; Y. L. Wang et al, 2019; C. Zhang et al, 2014; Y. Zhou et al, 2011), which are widely distributed in the central‐southern regions of the GXR, suggesting that most of the magmatic emplacement crystallization ages of these rocks ranged from 140 to 125 Ma and the magmatic activity peaked during the Early Cretaceous (Table 4; Figure 8; Ge et al, 2005; Tai et al, 2021; W. L. Xu et al, 2013; X. P. Yang et al, 2019). In this paper, we first report the new high‐precision zircon U–Pb ages for the granite porphyry (123 ± 1.2 Ma and 122 ± 1 Ma) from the Taipingtun area, approximately 15 km NE of Ulanhot (Figure 2).…”

“…Recently, growing evidence has implied that the Mongol‐Okhotsk Ocean Plate had been subducted since the Early‐Middle Permian (Mi, Lü, Yan, Zhao, & Yu, 2019), closing in a scissor‐like pattern with a west‐east direction (Donskaya, Gladkochub, Mazukabzov, & Ivanov, 2013; Tomurtogoo, Windley, Kroner, Badarch, & Liu, 2005), and finally closed in its eastern end‐member during the Late Jurassic‐Early Cretaceous (Kravchinsky, Cogne, Harbert, & Kuzmin, 2002). In addition, the NE‐trending Mongol‐Okhotsk Ocean suture zone was inconsistent with the NNE‐trending main vein of the GXR, suggesting that the Mongol‐Okhotsk Ocean tectonic domain might lack the controlled magmatic activity of the GXR during the Early Cretaceous (He et al, 2017; Tai, Mi, Wang, Li, & Kong, 2021). However, the subduction of the PPO plate is a multistage evolution with various orientations (Suo et al, 2017; J. Tang, Xu, et al, 2018; W. L. Xu et al, 2013; X. P. Yang et al, 2019; R. X. Zhu & Xu, 2019), and subduction beneath Eurasia occurred no later than the Early Jurassic (Cui et al, 2020; Ji et al, 2019; Suo et al, 2017; J. Tang, Xu, et al, 2018; J.…”