Magmatic underplating beneath the Rajmahal Traps: Gravity signature and derived 3-D configuration

Journal of Earth system science

A P Singh1¹  Bijendra Singh1¹  Niraj Kumar1¹ 

[1] National Geophysical Research Institute, Uppal Road, Hyderabad 500 007, India$$

关键词: Rajmahal Traps;    mantle plume;    magmatism;    crustal underplating;    Bouguer anomaly.;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

The early Cretaceous thermal perturbation beneath the eastern continental margin of the Indian shield resulted in the eruption of the Rajmahal Traps. To understand the impact of the magmatic process that originated in the deep mantle on the lower crustal level of the eastern Indian shield and adjoining Bengal basin the conspicuous gravity anomalies observed over the region have been modelled integrating with available geophysical information. The 3-D gravity modelling has delineated 10–15km thick high-density (𝜌 = 3.02 g/cm3) accreted igneous layer at the base of the crust beneath the Rajmahal Traps. Thickness of this layer varies from 16km to the west of the Rajmahal towards north to about 12km near Kharagpur towards south and about 18km to the east of the Raniganj in the central part of the region. The greater thickness of the magmatic body beneath the central part of the region presents itself as the locus of the potential feeder channel for the Rajmahal Traps. It is suggested that the crustal accretion is the imprint of the mantle thermal perturbation, over which the eastern margin of the eastern Indian shield opened around 117Ma ago. The nosing of the crustal accretion in the down south suggests the possible imprint of the subsequent magmatic intrusion along the plume path.

【 授权许可】

Unknown