Deep Geological Structures Associated With Terrestrial Volcanic Hydrothermal Metallogenic System: Evidence From Geophysical Survey in Taohemu Superlarge Silver‐Polymetallic Deposit, Inner Mongolia

Abstract

Abstract Taohemu deposit is a superlarge silver‐polymetallic deposit discovered in the Great Xing'an Range metallogenic belt of China in recent years. The deposit occurs in the terrestrial volcanic rock sequences of Late Jurassic age. The ore bodies consist mainly of rhyolitic tuffs, brecciated tuffs, and volcanic breccia bearing Ag‐Pb‐Zn mineralization, and are largely conformable with the surrounding layered volcanic and volcaniclastic rocks with a gradual transitional relationship manifesting as strata‐bounded features in general. The mineralization system appears to be generally controlled by a paleo‐volcanic chamber. It is suggested that the late volcanic hydrothermal fluids flowed within the permeable layers of rhyolitic pyroclastics consisting mainly of volcanic breccias and breccia‐bearing tuffs. This resulted in the formation of superlarge Ag‐Pb‐Zn polymetallic ore deposit metasomatism and fracture filling. The majority of the deposit occurs as shallowly dipping concealed ore bodies, as defined by sparsely distributed drill holes. Because of its short discovery history, new mineralization style and low degree of comprehensive research, the boundaries of most ore bodies have not been effectively delineated along vertical and lateral extensions. At present, it is crucial to strengthen the comprehensive studies on the deposit, conduct more detailed geological exploration, and establish the metallogenic and prospecting models. For this reason, we have designed and implemented long sections of magnetotelluric (MT) and controlled‐source audio magnetotelluric (CSAMT) sounding across the Taohemu ore field and obtained a large number of geological structures and valuable underground exploration results that provided reliable geophysical support for promoting deep resource exploration.

Keywords

• terrestrial volcanic hydrothermal metallogenic system
• strata‐bounded ore body
• paleo‐volcanic chamber
• geophysical survey