Structural Ore-controlling Model for the Super-large Hadamengou Gold Deposit in Inner Mongolia, China

Abstract

Controversy is ongoing regarding the relationship between ore formation and the structural evolution of the Hadamengou gold deposit. To address this issue, we conducted a comprehensive investigation of mineralization-related structures, geochronology and Fe isotopes. From the perspective of spatial evolution, hydrothermal fluids originating from the Shadegai and Xishadegai plutons have extracted accumulated ore-forming elements from the Wulashan Group (Ar₂WL) and then evolved, initiating at Exploration Line 11 and migrating eastwards and westwards along the EW-trending thrust fault system to form orebodies. From the temporal evolution standpoint, the Wulashan Group (Ar₂WL) experienced diagenesis (2591.00 Ma to 2204.00 Ma) and metamorphism (2074.00 Ma to 1625.00 Ma) from late Neoarchean to early Paleoproterozoic, when ore-forming materials were initially accumulated; in the early Paleozoic (440.71 Ma to 425.00 Ma), the collision led to the formation of early-stage EW-trending imbricated thrust faults, which established a fundamental structural framework for the orefield and further accumulated ore-forming materials; from the late Paleozoic to the Mesozoic, multiple subsequent episodes of regional tectonic-magmatic-hydrothermal events have superimposed, modified and reactivated the thrust fault system. Notably, the Triassic period, particularly between 245.00 Ma and 217.90 Ma, is considered to be a primary ore-forming stage. In summary, the intricate relationship between ore-formation and structural evolution has been fundamentally elucidated.