Generation of Deccan Trap magmas

Journal of Earth system science

Gautam Sen1¹ 

[1]Deccan lavas can be grouped into stratigraphic subdivisions based on their geochemistry

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关键词: Deccan Trap;    giant Plagioclase basalt;    age;    contamination;    fractional crystallization;    magma generation.;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

Deccan Trap magmas may have erupted through multiple centers, the most prominent of which may have been a shield volcano-like structure in the Western Ghats area. The lavas are predominantly tholeiitic; alkalic mafic lavas and carbonatites are rare. Radioisotope dating, magnetic chronology, and age constraints from paleontology indicate that although the eruption started some 68 Ma, the bulk of lavas erupted at around 65-66 Ma. Paleomagnetic constraints indicate an uncertainty of ± 500, 000 years for peak volcanic activity at 65 m.y. in the type section of the Western Ghats. Maximum magma residence times were calculated in this study based on growth rates of "giantplagioclase" crystals in lavas that marked the end phase of volcanic activity of different magma chambers. These calculations suggest that the > 1.7 km thick Western Ghats section might have erupted within a much shorter time interval of ∼55,000 years, implying phenomenal eruption rates that are orders of magnitude larger than any present-day eruption rate from any tectonic environment. Other significant observations/conclusions are as follows:Deccan lavas can be grouped into stratigraphic subdivisions based on their geochemistry;

【 授权许可】

Unknown