Geochemistry and Zircon U–Pb Geochronology of the Zhuxi Granites in the Jingdezhen Area, Jiangxi Province, China: Implications for the Mesozoic Tectonic Development of South China

Hailong Huo,Ning Li,Yongjun Di,Xiaolong He,Bojie Hu,Zhengle Chen,Da Zhang

doi:10.3390/min12030283

Abstract

Mesozoic granitic magmatism in Northeastern Jiangxi, China is of tectonic significance for the evolution of the South China Block. Whole-rock geochemical and zircon U–Pb geochronological and Lu–Hf isotopic data for Mesozoic Zhuxi granites in the Jingdezhen area of Northeastern Jiangxi were presented. The Zhuxi granites are composed of granodiorite, biotite granite, and two-mica granite. Zircon LA–ICP–MS U–Pb isotopic analyses indicated emplacement at 159–147 Ma. The granites are characterized by a strongly peraluminous nature with high A/CNK values (>1.1), high SiO2 (66.09–74.46 wt.%) and K2O (3.50–5.52 wt.%) contents, depletion in Ba, Nb, Ce, Sr, and Ti, moderately negative Eu anomalies (Eu/Eu* = 0.40–0.63), enrichment in LREE, and depletion in HREE ((La/Yb)N > 7.43). The A/CNK > 1.1, widespread aluminum-rich minerals (e.g., muscovite and tourmaline), indicating they are S–type granites and belong to muscovite–bearing peraluminous granites (MPG). The Zhuxi granites exhibited negative εHf(t) values (−9.9 to −3.7) and the TDM2 model ages of 1840–1442 Ma indicated derivation from ancient crustal sources. The magma is possibly caused by the subsequent process of intracontinental subduction. It is inferred that the Mesozoic magmatism in Northeastern Jiangxi was associated with oceanic–continental convergence of the Paleo–Pacific and Eurasian plates as well as the intracontinental subduction of the Yangtze and Cathaysia blocks. The Zhuxi granites highlight the primary role of oceanic–continental convergence and intracontinental subduction in early Yanshanian granitoid magmatism in South China.

Highlights

The South China Block (SCB) comprises the Yangtze Block to the north and Cathaysia Block to the south, which amalgamated during the Neoproterozoic after a collision along the Jiangnan orogenic belt (Figure 1a) [1,2,3,4,5,6,7,8]
As an important junction of the Yangtze and Cathaysia blocks, Northeastern Jiangxi provides a window for the study of intracontinental
As an important junction of the Yangtze and Cathaysia blocks, Northeastern Jiangxi provides a window for the study of intracontinental subduction of the SCB and magmatic–tectonic processes in the region, scuobndturicbtuiotninogfttohoeuSrCuBnadnedrstmanagdminagtiocf–ttheceteovnoicluptrioonceosfseths einenthtierereSgCioBn(,Fciognutrreib1ubt)i[n1g1,t1o9o,2u8r– u3n3d].erstanding of the evolution of the entire SCB (Figure 1b) [11,19,28,29,30,31,32,33]

Summary

Introduction

The South China Block (SCB) comprises the Yangtze Block to the north and Cathaysia Block to the south, which amalgamated during the Neoproterozoic after a collision along the Jiangnan orogenic belt (Figure 1a) [1,2,3,4,5,6,7,8]. Neoproterozoic basement units of the Jiangnan Orogenic Belt in Northeastern Jiangxi are known as the Shuangqiaoshan Group (Figure 1b,c) [30,34,45,46,47,48]. The Shuangqiaoshan Group is the dominant folded basement strata in the eastern Jiangnan orogen, and is exposed mainly in the northwestern, northern, and northeastern parts of Jiangxi Province (Figure 1b) [14]. It is mainly composed of a thick pile (2678–5472 m) of pelitic and sandy sedimentary rocks with lesser volcanic rocks [14,48]. U, Th, and Pb ratios are presented in Supplementary Table S2

Major– and Trace–Element Analyses

Zircon Hf Isotopic Analyses

Petrography

Geochemistry

Findings

Regional Magmatism of the Northeast Jiangxi and Adjacent Area