Construction of a Long-Lived Hydrothermal Architecture for W, Au-Sb Deposits During Variscan Belt Thermal Collapse, French Massif Central (330–295 Ma)

Since pioneering fluid-flow models for the Iberian and French Variscan belt, advances in geochronology, thermochronology, and geodynamic modeling have improved our understanding of late Variscan crustal evolution. New datasets suggest tungsten and gold mineralization do not represent distinct metallogenic events, but successive expressions of a long-lived hydrothermal evolution linked to crustal melting, granite emplacement, exhumation, and thermal collapse. Fluid drainage along shear zones drove silicification and arsenic precipitation, building an efficient trap for later gold deposition. As the hot, rapidly exhumed crust evolved, it progressively became a gold-bearing hydrothermal system, its architecture developing from the mountain-range scale down to microfractures. The resulting metallogenic model is therefore hierarchical rather than episodic, built through progressive construction of efficient traps. Quartz first forms the mechanical trap, massive deposition creating competent bodies prone to repeated brittle reactivation. Arsenopyrite is then deposited along the same zones, within shear environments reactivated during exhumation, establishing the principal chemical trap for gold enrichment with a polymetallic signature (Ag, Sb, Pb, Cu, Zn, Bi, Te). This late stage results from repeated microfracturing, promoting remobilization and native gold enrichment. The economically significant gold stage thus culminates this hydrothermal evolution, reflecting the progressive self-organization of the system during orogenic collapse.