Hello Chetan

Top universities offering phD in geology are mentioned here

Aligarh muslim university

Banaras Hindu university

IIT kanpur

University of Delhi

Amity university , Noida

Panjab university , Chandigarh

Alagappan university , Andhra Pradesh

IISER , Kolkata

Indian Institute of science education and research , Behrampur

Indian Institute of science education and research, pune , maharshtra

Guahati university

Patna university

IIT Roorkee

For detsils kindly visit the link given below

https://university.careers360.com/colleges/list-of-phd-in-geology-universities-in-india