Informatics Publishing Limited

K. N. Srinivasan ¹, V. Ganesan ², D. Roop Kumar ¹, K. S. Murti ¹, N. V. Rao ³

Affiliations
1 Geological Survey of India, Operations: Andhra Pradesh, Hyderabad, IN
2 Geological Survey of India, Operations: Tamil Nadu, Madras, IN
3 Geological Survey of India, Operations: Andhra Pradesh, Hyderabad

Abstract

The anorthosite of Sripuram is a syn - to late - tectonic concordant intrusive into the rocks of Khammam Schist Belt (KSB). Its major element Chemistry is comparable to Archaean anorthosites.

Keywords

Petrology, Anorthosite, Granulite, Khammam Schist Belt, Andhra Pradesh.

Full Text

     

K. R. P. Rao ¹, T. A. K. Reddy ¹, K. V. S. Rao ¹, K. S. B. Rao ¹, N. V. Rao ¹

Affiliations
1 Geological Survey of India, Operation: Andhra Pradesh, Hyderabad 500 068, IN

Abstract

Apart from the well known occurrence of kimberlites in south India at Wajrakarur in Anantapur district, kimberlites were located by Geological Survey of India (GSI), during 1984-85 around Maddur and Narayanpet areas in Mahabubnagar district of Andhra Pradesh. Landsat imagery and photo-interpretation studies followed by intense geological traverses including stream sediment surveys, launched during 1994-96, led to the discovery of 20 additional kimberlites in the western part of Mahabubnagar district, Andhra Pradesh and in the adjoining Gulbarga district, Karnataka, thus reporting kimberlite for the first time from the state of Karnataka. A total of 30 kimberlites have been reported in this field named as "Narayan pet Kimberlite Field" (NKF).

The kimberlites are emplaced along E-W and NW-SE trending major faults and associated NE-SW tear faults in the Peninsular Gneissic Complex carrying enclaves of Dharwar greenstones of Gadwal schist belt. These kimberiites occur both as small bodies of a few metres across and also as dykes with a strike length of about 2 km. The characteristic mineral assemblages and textures indicate that these bodies correspond to hypabyssal facies or ischolar_main zone kimberlites. The indicator mineral suite present in these rocks are olivine, chrome diopside, magnesian ilmenite, chrome spinel, ai1d rare pyrope garnet Mantle xenoliths are rare, nevertheless spinel Iherzolite; abundantly found in two kimberlites.

All the kimberlites of NKF are depleted in SiO₂ (∼ 35%), potassic (K₂O >Na₂O) and magnesium rich (MgO >20%). The REE abundance of these kimherlites is consistent with their derivation by partial melting of mantle and subsequent fractional crystallisation of the melt. The similarity of petrological and geochemical characters of these kimberlites indicate that all the kimberlites of NKF are derived from similar source in the upper mantle.

Preliminary processing and testing of some of the kimberlite bodies have not yielded any diamonds so far. However, the reported stray diamond finds in the Krishna and Bhima River gravels indicate the presence of diamondiferous kimberlites further south and southwest of the area.

Keywords

Economic Geology, Geochemistry, Kimberlite, Andhra Pradesh, Karnataka.

Full Text

     

G. Suresh ¹, K. N. Srinivasan ¹, D. Roopkumar ¹, N. V. Rao ¹

Affiliations
1 Geological Survey of India, P.O. Bandlaguda, Hyderabad - 500 068, IN

Abstract

A linear body of gabbro-anorthosite has been recognised as a syn-to-late kinematic intrusion within the calc-alkaline granitoid suite of the Eastern Dharwar Craton, having the characteristics of layered mafic intrusion (LMI) and major oxide composition similar to massif type anorthosite.

Keywords

Petrology, Anorthosite, Gabbro, Andhra Pradesh.

Full Text

     

S. Paul , N. V. Rao

Abstract

The purpose of this note is to examine the long-run demand-potential for electric motors in India. By "long run", we mean a period of five years which is also the time span used hy the Government of India in its planning. The nature of the product and the time dimension involved are such that consumer surveys to forecast the demand potential for motors will be of little avail. Projections of demand trends must be based on the relationships between motor-demand and some meaningful independent variables which can be justified on economic and technical grounds. Because of the relatively long-term nature of the forecast, the focus will be on over-all demand-trends and not on detailed estimates of the demand for different types of motors.

Full Text