Identification of Subsurface Structures and their Inferences from Regional Magnetic (Total Field) Survey for loci of Kimberlite Pipe Rocks in the Western part of Anantapur and Adjoining Areas, Andhra Pradesh.

摘要

The Magnetic (Total Field) survey has recorded characteristic magnetic responses over different litho units with significant contour pattern trending in NW-SE, NE-SW, N-S and E-W directions in the form of magnetic linears, breaks, gradients and circular and bipolar anomalies, indicating fault/contact in between the formations which are responsible for the formation of cross structural trends. The magnetic map has shown a variation of 930 nT ranging from -561 nT to +369 nT in the area. The magnetic map has clearly traced the Ramagiri- Pēnakacherla schist belt from Kuderu to Ramagiri in the form of linear feature aligned in N-S direction with moderate variation of -50nT to 100nT and sparse contour pattern. The rocks exposed in the area are of PGC, Dharwar, schist belt, mafic gabbro/dolerite dykes and small plutons of pink/grey hornblende biotite granite. The general trend of formations is in NNW-SSE to N-S direction with moderate to steep dips. The magnetic map has delineated a few inferred structural features. The intersection of NW-SE, NE-SW and E-W magnetic linears observed around Alamuru, Raptadu, Kuderu, Atmakuru, Ramasagaram, Golla, west of Sirpi and near Maddelacheruvu, Known as "Joints" needs further detailed study from the point of mineral exploration as most of the kimberlite bodies are identified near these intersections. Three test pits were opened over the anomaly zones and the analysis of the rock/soil samples were quite encouraging for the path finder elements of Kimberlite clan of rocks. A few blocks were recommended for further detailed geophysical surveys.