Xu, Chongwen, Zhao, Xu, Huizenga, Jan Marten, Wei, Junhao, Hu, Yue, and Zhao, Zhixin (2023) Garnet U-Pb dating and magnetite geochemistry: Constraints on the origin of Fe mineralization in the Huogeqi polymetallic deposit, Northern China. Ore Geology Reviews, 163. 105747.

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Abstract

The Huogeqi Fe polymetallic deposit, which contains 48.17 Mt Fe, occurs in tremolite-diopside rocks of the Neoproterozoic Langshan Group in the north China. This study focuses on the magnetite mineralogy, texture and chemical composition, and U-Pb geochronology of garnet associated with magnetite and zircon from the granitoid related to mineralization in order to constrain the origin of Fe mineralization in Huogeqi deposit. LA-ICPMS U-Pb dating of magnetite-bearing garnets yields a lower intercept age of 277.5 ± 8.7 Ma, which is coeval with the emplacement age of the mineralized-related granitoid (275.3 ± 1.3 Ma). Three types of magnetite were formed in the Huogeqi deposit, including Mt-A (coarse-grained disseminated), Mt-B (stratiform and fine-grained dense disseminated), and Mt-C (massive). The Mt-A can be subdivided into high-Ti Mt-A1 and relatively low-Ti porous and fractured Mt-A2. The Mt-B can be subdivided into porous Mt-B1 with relatively high V and low Ti contents, dark porous Mt-B2 with a relatively low V contents, porous inclusion-rich Mt-B3 with low Fe and V contents, and high Si and Mg contents, and less-porous Mt-B4 with low Si and Mg contents. The Mt-C includes porous Mt-C1 with a low Ti contents and high Si, Al, Mn contents and less-porous Mt-C2 with low Si, Al, and Mn contents. The decreasing Ti and V contents in the subsequent magnetite types indicate progressive cooling of the mineralizing fluid, increasing oxygen fugacity, and more intense fluid-rock interaction. Dissolution and reprecipitation played an important role in the formation of different generations of magnetite of Mt-B and Mt-C. The magnetite from Huogeqi deposit has a high Ni/Cr mass ratio, a high Fe content, and a high (Ca + Al + Mn) value, and a low V content, a low Ni/(Cr + Mn) mass ratio, and a low (Ti + V) value. These geochemical characteristics indicate that the magnetite has a hydrothermal origin in a skarn-type deposit, which is related to Early Permian magmatism in the Langshan area in north China.

Item ID:	81175
Item Type:	Article (Research - C1)
ISSN:	1872-7360
Keywords:	Huogeqi polymetallic deposit; Garnet U-Pb dating; Langshan; Magnetite; Mineral geochemistry
Copyright Information:	© 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/bync-nd/4.0/).
Date Deposited:	21 Nov 2023 21:56
FoR Codes:	37 EARTH SCIENCES > 3705 Geology > 370502 Geochronology @ 50% 37 EARTH SCIENCES > 3703 Geochemistry > 370302 Inorganic geochemistry @ 50%
SEO Codes:	28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280107 Expanding knowledge in the earth sciences @ 100%
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