TITLE:
Structural Evolution of Kollapur Region in the Northwestern Margin of Cuddapah Basin and, Eastern Dharwar Craton, South India: New Insights from Gravity Anomalies
AUTHORS:
Linga Swamy Jogu, Udaya Laxmi Gakka
KEYWORDS:
Amphibolite Schist, Kimberlite and Lamproite, Gravity Anomalies, Euler 3D Depth, Gravity Modelling
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.13 No.2,
February
24,
2025
ABSTRACT: To decipher both shallow and deeper structural features that may control the emplacement of Kimberlite/Lamproite bodies in basement-exposed and covered areas, a detailed gravity survey was conducted on the northern bank of the Krishna River in the Kollarpur region of the Proterozoic Cuddapah Basin, within the Eastern Dharwar Craton. The study revealed an overall basement disposition dipping from south to north, controlled by a set of parallel E-W and NW-SE trending faults. In the northeastern part of the study area, the high-gravity zone corresponds to high-density source rocks at both shallow and deeper levels within the granite-gneissic basement. The residual gravity map highlights the disposition of high-density shallow source bodies as elliptical highs, located at Narlapur, Kalwakole, and Yelur in the eastern part. These residual gravity highs correspond to enclaves of amphibolite schist and BIF bands within granite-gneissic rocks. In the covered region of the southern part, the overall gravity low zone indicates the distribution of sediments with a thickness of about 1 km. Several NW-SE, N-S, NE-SW, and E-W structural features were delineated from the gravity survey. A major E-W gravity gradient along the northern margin of the Cuddapah and Kurnool groups of sediments is interpreted as a deep-rooted boundary fault. Parallel to this boundary fault, two NW-SE gravity gradients were identified in the northern and central parts within the Archean granite-gneissic basement rocks. Depth extensions of these major structures exceed 1 km. The N-S and NE-SW structures, although shorter in strike length, intersect with the major NW-SE and E-W structures. Some of these intersection zones correspond to known Kimberlite/Lamproite occurrences in both covered and basement-exposed areas. Based on these findings, potential loci for Kimberlite/Lamproite exploration have been delineated along the northern bank of the Krishna River in the Kollarpur region.