Exhumation and preservation of magmatic sulfide deposits in Eastern Tianshan, NW China as revealed by zircon and apatite (U-Th)/He thermochronology

• Huangshandong, Hulu and Tulaergen deposits experienced two cooling stages. • The rapid cooling stage from Late Permian to Triassic is the critical stage. • The differences in morphology of deposits indicate different exhumation history. • The exposure of magmatic Cu-Ni sulfide deposits requires extensive exhumation. The Central Asian Orogenic Belt (CAOB) hosts a number of magmatic Ni-Cu sulfide deposits associated with mafic–ultramafic intrusions. These deep-seated intrusions were exhumed to the surface through orogenic processes, so the history of uplift and exhumation plays a crucial role in their preservation. Understanding this history has significant implications for exploration. We present zircon and apatite (U-Th)/He low-temperature thermochronology data from the Huangshandong, Hulu, and Tulaergen intrusions, located in the Jueluotage of Eastern Tianshan along the southern boundary of the CAOB. These three intrusions show consistent Permian zircon U-Pb ages, and their thermal history reveals two stages of uplift and exhumation. The first stage, a period of rapid uplift from Late Permian to Triassic, has been attributed to the far-field effects of the collision between the Qiangtang and Eurasian continent. Following this, a prolonged period of planation in Tianshan from Jurassic to the present day, marked the second stage, characterized by gradual cooling with cooling rates of 0.56°C/Myr, 0.69°C/Myr, 0.59°C/Myr and exhumation rates of 19.0 ± 3.0 m/Myr, 24.0 ± 4.0 m/Myr, 20.5 ± 3.5 m/Myr for the Huangshandong, Hulu, and Tulaergen intrusions, respectively. These cooling and exhumation rates suggest minor differences in exposure among the three intrusions during this slow cooling stage. However, stratigraphy, morphology, and proportions of ultramafic to mafic indicate that Tulaergen and Hulu may have experienced more extensive erosion. Therefore, the initial rapid cooling stage contributed to the differential exposure of these deep intrusive bodies, while the slower cooling stage favored the preservation of mineral deposits due to the limited exposure. Additionally, the Jueluotage region demonstrates a trend of stronger exhumation in the east than in the west, resulting in the exposure of Cu-Ni deposits at the surface in the eastern part. Therefore, we further hypothesize that regions within orogenic belts that have experienced short-term rapid uplift followed by long-term gradual cooling are favorable for exploring deep-seated mineralized intrusions.