Contents: Foreword and preface. Text. 1. Layout of Gravity-Magnetic Stations: Scale 1: 1,000,000. 2. Geological and Gravity Map of Rajasthan-Gujarat Shield: Scale 1: 2,250,000. 3. Bouguer Gravity Map of Rajasthan-Gujarat Shield: Scale 1: 1,000,000. 4. Stack of Regional Gravity-Magnetic (VF) Profiles: Scale 1: 1,000,000. 5. Residual Gravity Map of Rajasthan-Gujarat Shield: Scale 1: 1,000,000. 6. Bouguer Gravity Maps for Rajasthan-Gujarat Shield: Scale: 1: 250,000.
From the Foreword: "This Atlas of Bouguer Gravity Maps of the Precambrian shield of Rajasthan and Gujarat incorporates the results of surveys carried out during 1976-'83. With the release of these maps, and altogether new approach to interpretation of the geology of this richly mineralised segment of the Indian shield is made possible. So far in this country, geophysical methods have been utilised in ore search more often as a tool for establishing the continuity of known mineralised zones. This has been a natural corollary to the methodology of exploration that has been pursued relying, as it did, on a study and probe of ancient mine workings. With the near exhaustion of such targets, the course of exploration in future has to depend on an in depth understanding - in the figurative as well as literal sense of the geology of terrains which are devoid of surface evidences of mineralisation and are often under extensive cover of soil and vegetation.
The gravity data now presented, or for that matter any data from such regional surveys, have to be viewed in a broader perspective of understanding the geological setting in its totality and embodying this understanding in models integrating the near-surface geology with deep crustal features. An attempt in this direction has been made by the authors and the geological configurations inferred by them at depth hold out possibilities of effectively guiding mineral exploration.
From gravity there is suggestion of Block Movements along deep fractures resulting in a prominent horst. The supracrustals over the horst are apparently resting over ridges and depressions in the basement which is dissected by deep fractures. The known sulphide occurrences are spatially coincident with the fracture systems flanking the ridges. This subsurface tectonic model needs to be supplemented by evidences from other geophysical methods as well as by geological and remote sensed data in order to arrive at a more comprehensive model. Such geological models alone may ultimately provide a sound and lasting basis for exploration programmes in the future."
