{"title":"Complex structure of the center Oktyabr’sky deposit, Norilsk district, Russia","authors":"","doi":"10.1016/j.jseaes.2024.106264","DOIUrl":null,"url":null,"abstract":"<div><p>The PGE-Cu-Ni Oktyabr’sky deposit, related to the Kharaelakh intrusion, contains the largest sulfide ore bodies in the world. Various models have been proposed to explain its formation based on the mineralogical and textural characteristics of the sulfide ores. However, the underlying structure of the intrusion, critical to understanding the deposit’s formation, has not been well studied until now. For the first time a 3D model of the center deposit with C-3 and C-4 orebodies representing its main part has been created. The model reveals that the intrusion in this area is a thin plate, rather than a tubular or honolithic body, as previously assumed. This morphology does not support the idea of ore formation by <em>in situ</em> reaction between primary magma and host rocks. Instead, sulfides were transported by magma from a deeper zone in the chamber. Within this area, two pulses of magma were identified, forming the Northern and Southern intrusive branches. They are similar in inner structure; however, some differences exist. The rocks of these intrusions are identical in terms of their major components but differ in metals (Cu/Ni ratios, Co, Zn, and V contents), which is particularly reflected in the composition of the chalcopyrite group of minerals. The picritic gabbro-dolerites presented in both intrusive bodies crystallized under similar conditions, namely, <em>T</em> and <em>fO2</em>, with an accuracy of the applied methods (±15 °C and ± 0.4 lg<em>fO<sub>2</sub></em>, respectively) from two portions of magma that differ from those of the taxitic gabbro-dolerites. Therefore, the Oktyabr’sky deposit has a more complex structure in its central part than has been previously reported. Considering earlier published data from the western and eastern parts, it can be concluded that the Karaelakh intrusion consists of several intrusive bodies rather than a single large massif that should be consider in future models.</p></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":null,"pages":null},"PeriodicalIF":2.7000,"publicationDate":"2024-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Asian Earth Sciences","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1367912024002591","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
The PGE-Cu-Ni Oktyabr’sky deposit, related to the Kharaelakh intrusion, contains the largest sulfide ore bodies in the world. Various models have been proposed to explain its formation based on the mineralogical and textural characteristics of the sulfide ores. However, the underlying structure of the intrusion, critical to understanding the deposit’s formation, has not been well studied until now. For the first time a 3D model of the center deposit with C-3 and C-4 orebodies representing its main part has been created. The model reveals that the intrusion in this area is a thin plate, rather than a tubular or honolithic body, as previously assumed. This morphology does not support the idea of ore formation by in situ reaction between primary magma and host rocks. Instead, sulfides were transported by magma from a deeper zone in the chamber. Within this area, two pulses of magma were identified, forming the Northern and Southern intrusive branches. They are similar in inner structure; however, some differences exist. The rocks of these intrusions are identical in terms of their major components but differ in metals (Cu/Ni ratios, Co, Zn, and V contents), which is particularly reflected in the composition of the chalcopyrite group of minerals. The picritic gabbro-dolerites presented in both intrusive bodies crystallized under similar conditions, namely, T and fO2, with an accuracy of the applied methods (±15 °C and ± 0.4 lgfO2, respectively) from two portions of magma that differ from those of the taxitic gabbro-dolerites. Therefore, the Oktyabr’sky deposit has a more complex structure in its central part than has been previously reported. Considering earlier published data from the western and eastern parts, it can be concluded that the Karaelakh intrusion consists of several intrusive bodies rather than a single large massif that should be consider in future models.
期刊介绍:
Journal of Asian Earth Sciences has an open access mirror journal Journal of Asian Earth Sciences: X, sharing the same aims and scope, editorial team, submission system and rigorous peer review.
The Journal of Asian Earth Sciences is an international interdisciplinary journal devoted to all aspects of research related to the solid Earth Sciences of Asia. The Journal publishes high quality, peer-reviewed scientific papers on the regional geology, tectonics, geochemistry and geophysics of Asia. It will be devoted primarily to research papers but short communications relating to new developments of broad interest, reviews and book reviews will also be included. Papers must have international appeal and should present work of more than local significance.
The scope includes deep processes of the Asian continent and its adjacent oceans; seismology and earthquakes; orogeny, magmatism, metamorphism and volcanism; growth, deformation and destruction of the Asian crust; crust-mantle interaction; evolution of life (early life, biostratigraphy, biogeography and mass-extinction); fluids, fluxes and reservoirs of mineral and energy resources; surface processes (weathering, erosion, transport and deposition of sediments) and resulting geomorphology; and the response of the Earth to global climate change as viewed within the Asian continent and surrounding oceans.