Citation: | Xue-zhong Yu, Yi-yuan He, Meng Wang, Jian Zhang, Xuan-jie Zhang, Zheng-guo Fan, 2020. Gravity and magnetic field characteristics and regional ore prospecting of the Yili ancient continent, West Tianshan, Xinjiang Uygur Autonomous Region, China, China Geology, 3, 104-112. doi: 10.31035/cg2020023 |
Gold, iron, copper, lead-zinc and other mineral exploration in West Tianshan, Xinjiang Uygur Autonomous Region, has made remarkable progress in recent years. However, due to the dispute on the tectonic division of West Tianshan, the ore-controlling factors and the regional metallogenic laws are controversial. The authors analyze regional gravity data and notice that the high-value region corresponds to the Yili ancient continent, thus the southeastern boundary of the Yili ancient continent is delineated. Comparative analysis of gravity, aeromagnetic and geologic data reveals that the Tulasu basin, where some medium to large epithermal gold deposits locate, lies above the Yili ancient continent; the Yili Carboniferous-Permian rift extends in E-W direction, numbers of copper deposits have been found in the mid-west section of the rift which lies above the Yili ancient continent, whereas few copper deposits have been discovered in the east section which is outside the Yili ancient continent. Accordingly, the Yili ancient continent may be rich in gold, copper and other metal elements; the metal-bearing hydrothermal solution moves up with the activity of magmatism, and deposits in the favorable places (the Tulasu basin and the Yili Carboniferous-Permian rift), forming numerous small and medium gold, copper deposits, as well as some large and super-large gold deposits. Therefore, the tectonic-magmatic hydrothermal zone above the Yili ancient continent should be the prospective area for epithermal gold and copper polymetallic deposits.
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Major geotectonic units in the eastern region of West Tianshan, Xinjiang Uygur Autonomous Region (modified from Qian Q et al., 2009). NNF–North Nalati fault; NTF–North Tarim fault; NTSZ–North Tianshan suture zone.
Geologic map of the Axi gold deposit (after Zhai W et al., 2009).
The Bouguer anomaly field of the study area.
Geophysical and geological maps of the Tulasu basin. (a)–the Bouguer anomaly field; (b)–aeromagnetic ΔT image with a reduction to the pole; (c)–regional geological map. 1–Quaternary; 2–sandy mudstone of Quaternary; 3–continental sediment of Middle-Upperr Triassic; 4–Taertaowu formation of Upper Permian; 5–Oiman Brak formation of Upper Carboniferous; 6–Dahara Junshan formation of Lower Carboniferous; 7–Nilka formation of Lower Silurian; 8–fine clastic rock-carbonate rock of Ordovician; 9–silty mudstone and limestone of Cambrian; 10–Kailaketi group of Sinian; 11–Kaiertasi group of Qingbaikou; 12–Songmuqieke group of Jixian; 13–the Middle Variscan plagiogranite; 14–the Middle Variscan granite-porphyry; 15–the Middle Variscan monzonitic granite; 16–the Middle Variscan granodiorite; 17–faults; 18–Pb-Zn deposits; 19–Cu deposits; 20–Au deposits.
Geophysical and geological maps of the copper deposits to the south of Nilka County. a–the Bouguer anomaly field; b–aeromagnetic ΔT image with a reduction to the pole; c–regional geological map. 1–Quaternary; 2–sandy mudstone of Quaternary; 3–continental sediment of Cretaceous; 4–coal-bearing strata in Middle-Lower Jurassic Toutunhe formation; 5–the sandy mudstone in Upper Permian Xiaoshayi formation; 6–the intermediate-basic continental volcanic rocks in Lower Permian Wulang formation; 7-Akesake formation of Lower Carboniferous; 8–Dahara Junshan formation of Lower Carboniferous; 9–the Late Variscan plagioclase granite porphyry; 10–the Late Variscan diorite porphyrite; 11–the Late Variscan diorite; 12–the Late Variscan diabasic porphyrite; 13–the Late Variscan monzonitic granite; 14–the Middle Variscan granite; 15–the Middle Variscan granite porphyry; 16–the Middle Variscan diorite; 17–faults; 18–Pb-Zn deposits; 19–Cu deposits; 20–Fe deposits.
The most prospective area for epithermal gold deposits exploration of in Yili ancient continent in West Tianshan, Xinjiang Uygur Autonomous Region.