Knowledge Management System Of Guangzhou Institute of Geochemistry，CAS
Hu, Wan-Long1,2; Wang, Qiang1,2,3,5 ; Tang, Gong-Jian1,2; Qi, Yue1,2; Wang, Jun1,2; Yang, Zong-Yong1,4; Sun, Peng1
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| First identification of Early Cretaceous mafic dikes in the Baingoin area, central Tibet: Implications for crust-mantle interactions and magmatic flare-up | |
| Source Publication | GEOLOGICAL SOCIETY OF AMERICA BULLETIN
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| ISSN | 0016-7606 |
| 2024 | |
| Volume | 136Issue:1-2Pages:846-860 |
| DOI | 10.1130/B36755.1 |
| Language | 英语 |
| WOS Research Area | Geology |
| Abstract | Mafic dikes are generally emplaced in extensional tectonic settings and provide key information regarding deep mantle processes and sources. The Bangong-Nujiang suture zone was formed by the collision of the Qiangtang and Lhasa terranes and experienced intense magmatism during the Early Cretaceous. However, the deep mantle processes and mechanisms involved in this magmatic flare-up (ca. 115 Ma) in the collisional belt remain controversial because of the lack of evidence for coeval mafic magmatism. Here, we present detailed petrological, geochronological, geochemical, and Sr-NdHf-O isotope data for the newly discovered hypersthene-bearing mafic dikes in the Baingoin area in the middle -eastern parts of the Bangong-Nujiang suture zone, central Tibet. Secondary ion mass spectroscopy (SIMS) zircon U-Pb dating showed that the mafic dikes were emplaced during 120-115 Ma. These mafic rocks are characterized by variable MgO contents (2.7-5.2 wt%) and Mg# values (38.5-52.8), slight enrichment in light rare earth elements (REEs; [La/ Yb]N = 7.5-8.1), relatively flat heavy REE patterns ([Gd/Yb]N = 1.75-1.84), and negative Eu, Ta, Nb, and Ti anomalies. The dikes also have relatively low initial 87Sr/86Sr ratios (0.7060-0.7062) and negative eNd(t) (-2.2 to -1.6) and positive eHf(t) (+2.5 to +3.6) values, and variable zircon eHf(t) (-2.2 to +7.2) and slightly elevated zircon delta 18O (5.6%0-7.0%0) values. These geochemical characteristics indicate that the mafic dikes were derived from an enriched lithospheric mantle source. However, compared with coeval magmatic rocks, the mafic dikes have relatively high eNd(t) and eHf(t) values, indicating that they contain a depleted mantle component. The mafic dikes contain clinopyroxene and orthopyroxene (i.e., hypersthene), indicative of derivation from a high -temperature magma source. Clinopyroxene-melt thermobarometry yielded a temperature range of 1167- 1213 degrees C, further supporting the involvement of a high -temperature asthenospheric component. Therefore, we suggest that the parental magmas of the Nakoulai mafic dikes were probably generated by the interaction between the asthenospheric mantle and overlying metasomatized lithospheric mantle. Combined with data from nearby Cretaceous magmatic rocks and sedimentary rocks, we suggest that the mafic dikes were generated in a postcollisional setting caused by upwelling of asthenospheric mantle owing to slab breakoff beneath the Bangong-Nujiang suture zone. Slab breakoff played a key role in the crust -mantle interactions and the onset of the magmatic flare-up in the middle -eastern parts of the Bangong-Nujiang suture zone. |
| WOS ID | WOS:001169922800001 |
| Indexed By | SCI |
| Citation statistics | |
| Document Type | 期刊论文 |
| Identifier | http://ir.gig.ac.cn/handle/344008/77413 |
| Collection | 同位素地球化学国家重点实验室 |
| Corresponding Author | Wang, Qiang |
| Affiliation | 1.Chinese Acad Sci, State Key Lab Isotope Geochem, Guangzhou Inst Geochem, Guangzhou 510640, Peoples R China 2.CAS Ctr Excellence Deep Earth Sci, Guangzhou 510640, Peoples R China 3.Univ Chinese Acad Sci, Coll Earth & Planetary Sci, Beijing 100049, Peoples R China 4.Chinese Acad Sci, Inst Geochem, State Key Lab Ore Deposit Geochem, Guiyang 550002, Peoples R China 5.Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Isotope Geochem, Wushan St, Guangzhou 510640, Peoples R China |
| Recommended Citation GB/T 7714 | Hu, Wan-Long,Wang, Qiang,Tang, Gong-Jian,et al. First identification of Early Cretaceous mafic dikes in the Baingoin area, central Tibet: Implications for crust-mantle interactions and magmatic flare-up[J]. GEOLOGICAL SOCIETY OF AMERICA BULLETIN,2024,136(1-2):846-860. |
| APA | Hu, Wan-Long.,Wang, Qiang.,Tang, Gong-Jian.,Qi, Yue.,Wang, Jun.,...&Sun, Peng.(2024).First identification of Early Cretaceous mafic dikes in the Baingoin area, central Tibet: Implications for crust-mantle interactions and magmatic flare-up.GEOLOGICAL SOCIETY OF AMERICA BULLETIN,136(1-2),846-860. |
| MLA | Hu, Wan-Long,et al."First identification of Early Cretaceous mafic dikes in the Baingoin area, central Tibet: Implications for crust-mantle interactions and magmatic flare-up".GEOLOGICAL SOCIETY OF AMERICA BULLETIN 136.1-2(2024):846-860. |
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