Comparison of the genesis of typical antimony deposits in the Xiangzhong Antimony Ore Belt, South China

Abstract

The Xiangzhong Antimony Ore Belt (XAOB), located in the central part of South China, is the most concentrated area of antimony mineralization in the world. However, the genesis of the deposits is still widely disputed. To investigate the ore-forming mechanisms and compare the genetic relationships among different antimony deposits in XAOB, we analyzed the trace element compositions of hydrothermal quartz in six typical deposits (Xikuangshan Sb, Banxi Sb, Woxi Sb-Au-W, Zhazixi Sb-W, Longkou Sb, and Longshan Au-Sb deposits) by fsLA-ICP-MS. The data show that Al, Sb, Ge, Li, Na, and K are the most enriched trace elements in quartz, and the main possible replacement mechanisms in these deposits are (Al³⁺, Sb³⁺) + (Li⁺, Na⁺, K⁺, H⁺) ↔ Si⁴⁺ and Al³⁺ + Ge⁴⁺ + (Li⁺, Na⁺, K⁺, H⁺) ↔ Si⁴⁺. The significant variations in trace element compositions of quartz from the six deposits reveal differences in their ore-forming mechanisms. The Xikuangshan deposit stands out with high Al, Rb, and Sr contents and a limited variation in Al, suggesting that acidic fluids may have facilitated a water–rock reaction. In contrast, quartz from the Woxi deposit shows low Al, Rb, and Sr contents with variations in Ti and Ge contents, indicating fluid boiling may have been responsible for Sb mineralization. Quartz from the Banxi, Zhazixi, Longkou, and Longshan deposits display low, variable Al and variable Ti and Ge contents, suggesting the Sb mineralization was caused by fluid mixing. The magmatic-hydrothermal system likely contributed to Sb mineralization in all deposits except the Xikuangshan deposit. In the Longkou and Longshan deposits, higher B and Ga contents in quartz suggest that a closer relationship with magmatic-hydrothermal system, with Indosinian granite providing both heat and fluids. The XAOB comprises distinct Sb metallogenic systems, which are differentiated by quartz characteristics: (1) the Xikuangshan mineralization system, primarily controlled by water–rock reactions and unrelated to the magmatic-hydrothermal system; (2) the Banxi-Woxi-Zhazixi mineralization system, where the magmatic-hydrothermal system contributed heat; and (3) the Longkou-Longshan mineralization system, granite provided both heat and fluids. This study refines existing metallogenic models for the XAOB and provides valuable insights for future exploration and prospecting.