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DOI | 10.1130/B35142.1 |
U-Pb monazite ages of the Kabanga mafic-ultramafic intrusions and contact aureoles, central Africa: Geochronological and tectonic implications | |
Zi, Jian-Wei1,2; Rasmussen, Birger1,3; Muhling, Janet R.3; Maier, Wolfgang D.4; Fletcher, Ian R.2 | |
2019-11-01 | |
发表期刊 | GEOLOGICAL SOCIETY OF AMERICA BULLETIN
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ISSN | 0016-7606 |
EISSN | 1943-2674 |
出版年 | 2019 |
卷号 | 131页码:1857-1870 |
文章类型 | Article |
语种 | 英语 |
国家 | Peoples R China; Australia; Wales |
英文摘要 | Mafic-ultramafic rocks of the Kabanga-Musongati alignment in the East African nickel belt occur as Bushveld-type layered intrusions emplaced in metasedimentary sequences. The age of the mafic-ultramafic intrusions remains poorly constrained, though they are regarded to be part of ca. 1375 Ma bimodal magmatism dominated by voluminous S-type granites. In this study, we investigated igneous monazite and zircon from a differentiated layered intrusion and metamorphic monazite from the contact aureole. The monazite shows contrasting crystal morphology, chemical composition, and U-Pb ages. Monazite that formed by contact metamorphism in response to emplacement of mafic-ultramafic melts is characterized by extremely high Th and U and yielded a weighted mean Pb-207/Pb-206 age of 1402 +/- 9 Ma, which is in agreement with dates from the igneous monazite and zircon. The ages indicate that the intrusion of ultramafic melts was substantially earlier (by similar to 25 m.y., 95% confidence) than the prevailing S-type granites, calling for a reappraisal of the previously suggested model of coeval, bimodal magmatism. Monazite in the metapelitic rocks also records two younger growth events at ca. 1375 Ma and ca. 990 Ma, coeval with metamorphism during emplacement of S-type granites and tin-bearing granites, respectively. In conjunction with available geologic evidence, we propose that the Kabanga-Musongati maficultramafic intrusions likely heralded a structurally controlled thermal anomaly related to Nuna breakup, which culminated during the ca. 1375 Ma Kibaran event, manifested as extensive intracrustal melting in the adjoining Karagwe-Ankole belt, producing voluminous S-type granites. The Grenvillian-aged (ca. 990 Ma) tin-bearing granite and related Sn mineralization appear to be the far-field record of tectonothermal events associated with collision along the Irumide belt during Rodinia assembly. Since monazite is a ubiquitous trace phase in pelitic sedimentary rocks, in contact aureoles of mafic-ultramafic intrusions, and in regional metamorphic belts, our study highlights the potential of using metamorphic monazite to determine ages of maficultramafic intrusions, and to reconstruct postemplacement metamorphic history of the host terranes. |
领域 | 地球科学 |
收录类别 | SCI-E |
WOS记录号 | WOS:000493796300006 |
WOS关键词 | THOMPSON NICKEL BELT ; KIBARAN BELT ; ZIRCON GEOCHRONOLOGY ; CAPRICORN OROGEN ; WESTERN TANZANIA ; SULFIDE DEPOSITS ; DYKE SWARM ; SM-ND ; MINERALIZATION ; GEOCHEMISTRY |
WOS类目 | Geosciences, Multidisciplinary |
WOS研究方向 | Geology |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/188058 |
专题 | 地球科学 |
作者单位 | 1.China Univ Geosci, State Key Lab Geol Proc & Mineral Resources, Wuhan 430074, Hubei, Peoples R China; 2.Curtin Univ, John de Laeter Ctr, Kent St, Bentley, WA 6102, Australia; 3.Univ Western Australia, Sch Earth Sci, Stirling Highway, Perth, WA 6009, Australia; 4.Cardiff Univ, Sch Earth & Ocean Sci, Pk Pl, Cardiff CF10 3AT, S Glam, Wales |
推荐引用方式 GB/T 7714 | Zi, Jian-Wei,Rasmussen, Birger,Muhling, Janet R.,et al. U-Pb monazite ages of the Kabanga mafic-ultramafic intrusions and contact aureoles, central Africa: Geochronological and tectonic implications[J]. GEOLOGICAL SOCIETY OF AMERICA BULLETIN,2019,131:1857-1870. |
APA | Zi, Jian-Wei,Rasmussen, Birger,Muhling, Janet R.,Maier, Wolfgang D.,&Fletcher, Ian R..(2019).U-Pb monazite ages of the Kabanga mafic-ultramafic intrusions and contact aureoles, central Africa: Geochronological and tectonic implications.GEOLOGICAL SOCIETY OF AMERICA BULLETIN,131,1857-1870. |
MLA | Zi, Jian-Wei,et al."U-Pb monazite ages of the Kabanga mafic-ultramafic intrusions and contact aureoles, central Africa: Geochronological and tectonic implications".GEOLOGICAL SOCIETY OF AMERICA BULLETIN 131(2019):1857-1870. |
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