The Wajilitag intrusion is one of the most important mafic–ultramafic layered intrusions in the Tarim Large Igneous Province (LIP) as it hosts significant Fe–Ti–V mineralization. Despite this, the ubiquitous zoned clinopyroxene in this intrusion have largely been overlooked, limiting our understanding of the magmatic processes by which it formed. Here, we utilize major- and trace-element compositions of clinopyroxene to assess the petrogenetic evolution of Wajilitag, including the pressure–temperature conditions of crystallization, the magmatic processes by which it evolved, and the processes that led to the formation of Fe–Ti–V mineralization. Four types of zoned clinopyroxene are identified based on texture and zoning patterns. Type 1 clinopyroxene is characterized by abrupt zones and contains rounded, irregularly resorbed high-Mg cores (Mg# = 80.5–85.2) surrounded by low-Mg rims (Mg# = 66.1–77.5). Type 2–1 clinopyroxene is characterized by oscillatory zoning in which the mantle (Mg# = 73.8–80.3) has notably higher Mg contents than the core (Mg# = 72.7–77.1) and rim (Mg# = 70.7–75.1). Type 2–2 clinopyroxene exhibits normal zoning, in which Mg# and Cr contents gradually decrease from the core through the mantle to the rim. Type 3 clinopyroxene displays prism sector ({-111}) and hourglass sector ({010} and {110}) zoning, the presence of which implies a low to moderate degree of undercooling (ΔT = 40–51 °C). Type 4 clinopyroxene is euhedral and exhibits complex zoning (Mg# = 70.7–77.7). Clinopyroxene-only thermobarometry for mafic rocks at Wajilitag delineate two distinct magma reservoirs — (1) a deep, high-temperature magma chamber at ∼ 9.9 km depth and (2) a shallow, low-temperature magma chamber at ∼ 5.9 km depth. The parental magma in the deep chamber was likely more primitive than that in the shallow chamber, forming the Cr–Mg-rich core of type 1 clinopyroxene; the more evolved nature of the magma in the shallow chamber formed Cr–Ni-depleted clinopyroxenes represented by clinopyroxene types 2–4 and the rim of type 1. The H2O contents of the parental magmas range from 1.3–2.3 wt% (average = 1.8 wt%) in the deep magma chamber and 0.8–3.0 wt% (average = 2.0 wt%) in the shallow chamber. Iron–Ti oxides in the Wajilitag intrusion crystallized from an Fe–Ti-rich, oxidized, and hydrous magma at pressures and temperatures of 0.4–1.6 kbar and 1096–1137℃, respectively, and then accumulated during magma replenishment and vigorous convection. The complex textural and compositional characteristics of clinopyroxene at Wajilitag indicate that the intrusion represents an open magmatic plumbing system beneath the Tarim LIP that was periodically replenished by evolved and hydrous magmas.
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