Formation and composition of the Late Cretaceous Gangdese arc lower crust in southern Tibet
Arc lower crust plays a critical role in processing mantle-derived basaltic melts into the intermediate continental crust, yet can only be studied indirectly or in exposed arc sections. Compared with the relatively well-studied oceanic arc sections (e.g., Kohistan and Talkeetna), the composition and...
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| Format: | Article |
| Language: | English |
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Springer Science and Business Media LLC
2020
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| Online Access: | https://hdl.handle.net/1721.1/128904 |
| _version_ | 1826210976362397696 |
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| author | Guo, Liang Jagoutz, Oliver E Shinevar, William J. Zhang, Hong-Fei |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Guo, Liang Jagoutz, Oliver E Shinevar, William J. Zhang, Hong-Fei |
| author_sort | Guo, Liang |
| collection | MIT |
| description | Arc lower crust plays a critical role in processing mantle-derived basaltic melts into the intermediate continental crust, yet can only be studied indirectly or in exposed arc sections. Compared with the relatively well-studied oceanic arc sections (e.g., Kohistan and Talkeetna), the composition and formation mechanisms of continental arc lower crust remain less clear. Here we present a geochronological and geochemical study on the Lilong Complex and the Wolong granitoids from the Gangdese arc deep crustal section in southern Tibet. The Lilong Complex is composed of the early (85–95 Ma) mafic-intermediate sequence and late (85–86 Ma) ultramafic sequence. The Lilong crustal section exposed crustal depth extending from ~ 42 to 17 km based on the geobarometry. The mafic-intermediate sequence is a damp (low H2O) igneous differentiation sequence characterized by the subsequent appearance of pyroxene → plagioclase → amphibole → biotite. The ultramafic sequence represents a wet igneous differentiation sequence composed of olivine → pyroxene → amphibole → plagioclase. The 74–84 Ma Wolong granitoids were formed by fractional crystallization of wet magma and intra-crustal assimilation. Calculated seismic properties of the Gangdese deep arc crust are comparable to the average continental crust at a similar depth. The average composition of the Gangdese arc lower crust is basaltic andesite with SiO2 of ~ 54 wt%. The highly incompatible elements in the Gangdese arc lower crust are systematically higher than those of the oceanic arc and are comparable with the estimates of lower continental crust, suggesting continental arc magmatism significantly contributes to the formation of continental crust. |
| first_indexed | 2024-09-23T14:58:27Z |
| format | Article |
| id | mit-1721.1/128904 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T14:58:27Z |
| publishDate | 2020 |
| publisher | Springer Science and Business Media LLC |
| record_format | dspace |
| spelling | mit-1721.1/1289042022-10-01T23:43:22Z Formation and composition of the Late Cretaceous Gangdese arc lower crust in southern Tibet Guo, Liang Jagoutz, Oliver E Shinevar, William J. Zhang, Hong-Fei Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Woods Hole Oceanographic Institution Arc lower crust plays a critical role in processing mantle-derived basaltic melts into the intermediate continental crust, yet can only be studied indirectly or in exposed arc sections. Compared with the relatively well-studied oceanic arc sections (e.g., Kohistan and Talkeetna), the composition and formation mechanisms of continental arc lower crust remain less clear. Here we present a geochronological and geochemical study on the Lilong Complex and the Wolong granitoids from the Gangdese arc deep crustal section in southern Tibet. The Lilong Complex is composed of the early (85–95 Ma) mafic-intermediate sequence and late (85–86 Ma) ultramafic sequence. The Lilong crustal section exposed crustal depth extending from ~ 42 to 17 km based on the geobarometry. The mafic-intermediate sequence is a damp (low H2O) igneous differentiation sequence characterized by the subsequent appearance of pyroxene → plagioclase → amphibole → biotite. The ultramafic sequence represents a wet igneous differentiation sequence composed of olivine → pyroxene → amphibole → plagioclase. The 74–84 Ma Wolong granitoids were formed by fractional crystallization of wet magma and intra-crustal assimilation. Calculated seismic properties of the Gangdese deep arc crust are comparable to the average continental crust at a similar depth. The average composition of the Gangdese arc lower crust is basaltic andesite with SiO2 of ~ 54 wt%. The highly incompatible elements in the Gangdese arc lower crust are systematically higher than those of the oceanic arc and are comparable with the estimates of lower continental crust, suggesting continental arc magmatism significantly contributes to the formation of continental crust. 2020-12-22T21:41:01Z 2020-12-22T21:41:01Z 2020-06 2019-12 2020-09-24T20:56:45Z Article http://purl.org/eprint/type/JournalArticle 0010-7999 1432-0967 https://hdl.handle.net/1721.1/128904 Guo, Liang et al. "Formation and composition of the Late Cretaceous Gangdese arc lower crust in southern Tibet." Contributions to Mineralogy and Petrology 175, 6 (June 2020): 58 © 2020 Springer-Verlag GmbH Germany, part of Springer Nature en https://doi.org/10.1007/s00410-020-01696-y Contributions to Mineralogy and Petrology Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ Springer-Verlag GmbH Germany, part of Springer Nature application/pdf Springer Science and Business Media LLC Springer Berlin Heidelberg |
| spellingShingle | Guo, Liang Jagoutz, Oliver E Shinevar, William J. Zhang, Hong-Fei Formation and composition of the Late Cretaceous Gangdese arc lower crust in southern Tibet |
| title | Formation and composition of the Late Cretaceous Gangdese arc lower crust in southern Tibet |
| title_full | Formation and composition of the Late Cretaceous Gangdese arc lower crust in southern Tibet |
| title_fullStr | Formation and composition of the Late Cretaceous Gangdese arc lower crust in southern Tibet |
| title_full_unstemmed | Formation and composition of the Late Cretaceous Gangdese arc lower crust in southern Tibet |
| title_short | Formation and composition of the Late Cretaceous Gangdese arc lower crust in southern Tibet |
| title_sort | formation and composition of the late cretaceous gangdese arc lower crust in southern tibet |
| url | https://hdl.handle.net/1721.1/128904 |
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