科研之友
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摘要
Not all the magma produced during the partial melting of the mantle always reaches the Earth's surface, Most of it cools and may freeze during its ascent through the lithosphere when the ascent rates are not sufficiently high. In continental flood basaltic provinces magmatic underplating is a quantitatively important mechanism of crustal growth and evolution. Beneath continental areas, likely areas to trap basaltic magmas are located near the Moho or within the crust. Seismic studies and other geophysical means have provided evidence for underplated bodies beneath the Hawaiian Islands, La Reunion, Ninetyeast ridge, and the Deccan Trap. However, the ubiquitous occurrence of cumulate xenoliths in the lavas is perhaps the best and most direct petrological evidence for the significance of magma intrusion and accumulation beneath continental areas. In this article, we review occurrence of suite of ultramafic xenoliths entrained in the alkaline lavas, especially the cumulate xenoliths from Mt. Sayala, Kutch region, Gujarat in the western part of Deccan Flood Basaltic Province, India and its implication in understanding sub-crustal level magmatic and crust-building processes. In relation to the underplating process we discuss the importance of various other igneous intrusions and their role in the tectonomagmatic evolution of this part of the Deccan Flood Basalt.
- 出版日期2008-6-25
