Enrichment of Coal-Hosted Graphite Deposits Caused by Magmatic Heat Transfer and Tectonic Stress at Feng County, Western Qinling Orogen, China
Author:
Feng Yangwei12ORCID,
Ren Yan1ORCID,
Lyu Lushi3
Affiliation:
1. Henan Province Engineering Research Center of Environmental Laser Remote Sensing Technology and Application, Nanyang Normal University, Nanyang 473061, China
2. State Key Laboratory of Continental Dynamics, Northwest University, Xi’an 710069, China
3. Aerophotogrammetrical Surveying and Remote Sensing Bureau, CNACG, Xi’an 710054, China
Abstract
China has ranked first worldwide in graphite imports in recent years, facing a graphite supply risk. Coal-hosted graphite is the focus of future graphite deposit exploration. The current research on the enrichment and mineralization mechanism of coal-hosted graphite is superficial, and the identification standard of coal-hosted graphite is incomprehensive, restricting the exploration of coal-hosted graphite mineral resources and the development of coal metamorphic evolution theory. In this study, the Caotangou–Meigoucoal-hosted graphite deposit in western Qinling Mountain was taken as a case study for dissection. Based on the data from 1/50,000 and 1/200,000 regional geological mapping and the data of graphite mines in the study area, the samples were systematically collected and analyzed to explore the mechanism of coal graphitization through a 1:5000 geological profile survey, 1/10,000 geological mapping in key areas, and the investigation and cataloguing of abandoned coal-hosted graphite adit. The result was that there were two main coal-hosted graphite ore bodies, striking from nearly east to west. The Rmax values of the samples were 7.23–8.15%, the average values of Vdaf were around 5.0%, the d002 value of the II ore body was 0.3433–0.3389 nm, the d002 value of the I ore body was mainly 0.3418–0.3429 nm, the graphitization degree G value of the II ore body was 8.14–59.30%, the graphitization degree G value of the II ore body was 12.79–25.58%. The II ore body was coal-hosted graphite, while some samples of the I ore body were coal-hosted graphite, and some samples were coal. The magmatic heat controls the thermal metamorphism of coal seams to form graphite. The closer the distance to the magma body, the larger the crystals, and the higher the euhedral degree, indicating the higher degree of coal seam metamorphism. The nearly north–south compressive structures mainly provided effective tectonic stress for the evolution of coal graphitization during the Yanshan period; the basic structural units (BSUs) rotated and rearranged, eventually forming a straight graphite structure, and tectonic stress catalyzed the graphitization process. The coal-hosted graphite deposits formed under the dual effects of magmatic heat transfer and tectonic stress.
Funder
Key R&D and promotion projects in Henan Province
Jiangxi Provincial Natural Science Foundation
Natural Science Foundation of China
Cultivation Fund of National Natural Science Foundation of Nanyang Normal University
Doctoral program of Nanyang Normal University
China’s Ministry of Education University-Industry Cooperative Education Program
Henan Province Undergraduate Innovation and Entrepreneurship Training Program
Teaching and research projects of Nanyang Normal University
Subject
Geology,Geotechnical Engineering and Engineering Geology
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