| Title | Carboniferous arc-related volcanism in SW Bogda Mountain, Northwest China, and its implications for regional tectonics |
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| Author | Memtimin, M; Pe-Piper, G; Piper, D J W ; Guo, Z J; Zhang, Y Y |
| Source | Lithos vol. 360, 105413, 2020., https://doi.org/10.1016/j.lithos.2020.105413 |
| Image |  |
| Year | 2020 |
| Alt Series | Natural Resources Canada, Contribution Series 20200251 |
| Publisher | Elsevier |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Area | Bogda Mountain; China |
| Lat/Long WENS | 87.5000 88.0000 43.8333 43.6667 |
| Subjects | igneous and metamorphic petrology; geochemistry; tectonics; orogenic regions; Upper Carboniferous; volcanism; geochemical analyses; tuffs; tectonic environments; volcanic studies; volcanic rocks;
Carboniferous |
| Illustrations | location maps; geological sketch maps; stratigraphic columns; photographs; photomicrographs; tables; ternary diagrams; plots |
| Released | 2020 02 13 |
| Abstract | The Upper Carboniferous of Bogda Mountain is a critical area for understanding final oceanic closure of the Junggar Ocean in the Central Asian Orogenic Belt (CAOB). The 4 km thick Liushugou and
Qijiaojing formations, comprising tuffs and lesser lavas that accumulated in a subsiding marine basin, were studied to understand the architecture and petrogenesis of the volcanic succession. Tuffs, lavas and hypabyssal intrusions are mostly of
calc-alkaline composition, ranging from basalt through anclesite and dacite to rhyolite, interbedded with rare high-K rocks of basaltic trachyandesite to trachyte composition. Clinopyroxene and Fe Ti oxides are the main fractionating minerals in the
calc-alkaline rocks. Plagioclase has altered to albite by sea-floor metasomatism. The rocks are enriched in LILE and show relative depletion in Ta and Nb, suggesting an arc-related origin. The tuffs and lavas pass northward into dominantly trachytic
rocks, suggesting a northward subducting, intra-oceanic arc to back-arc system, with polarity contrary to previous literature, that was active from the time of the Kalamaili arc collision (similar to 350 Ma) to shortly after the North
Tianshan-Junggar collision (similar to 315 Ma). Following that collision, West Junggar experienced sinistral strike-slip deformation, and related crustal scale faults in Bogda Mountain allowed the rise of basaltic magma, forming pillow lavas and
hyaloclastites in a deepening basin. Finally, in the latest Carboniferous, the subduction-related volcanism ended and the Bogda basin was then onlapped by turbidites. The recognition of northward subduction in the Bogda segment of the CAOB has
regional implications for final closure of the Junggar Ocean. Comparison with published data from Kalamaili, the Junggar Basin, West Junggar and Arbassy demonstrates three tectonic phases with different volcanism, sedimentation and deformation in
different parts of the amalgamating orogen. |
| GEOSCAN ID | 326663 |
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