Active rifting and bimodal volcanism in Proterozoic Papaghni sub-basin, Cuddapah basin (Andhra Pradesh), India

Present study is carried out for delineation of Groundwater Potential Zones (GWPZ) in Western part of Cuddapah basin, Southern India using Remote Sensing (RS), Geographical Information System (GIS) and Analytical Hierarchy Process (AHP). Various categorized thematic maps: geology, geomorphology (GM), slope, soils, lineament density (LD), drainage density (DD) and gorundwater levels fluctuations (GWLF) were used for mapping and delineation of GWPZs. Suitable and normalized weights were assigned based on AHP to identify GWPZ. The GWPZ map was categorized into five GWPZs types: very poor, poor, moderate, good and very good. About 1.48% (6.05 km2) area is classified in ‘very good’, 25.95% (106.07 km2) in ‘good’, 47.11% (192.53 km2) in ‘moderate’, 22.12% (90.38 km2) in ‘poor’ and 3.34% (13.66 km2) in ‘very poor’ category. The acquired outcomes were validated with water levels fluctuations in pre- and post-monsoon seasons. GIS-based multi-criteria decision making approach is useful for preparation of precise and reliable data. The AHP approach, with the aptitudes of the geospatial data, various data bases can be combined to create conceptual model for identification and estimation of GWPZs.

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X-ray crystallography and mineral chemistry of bastnaesite from Kanigiri granite, Prakasam district, Andhra Pradesh, India

Open Geosciences ◽

10.2478/s13533-012-0187-7 ◽

2014 ◽

Vol 6 (4) ◽

Author(s):

Yamuna Singh ◽

G. Nagendra Babu ◽

R. Viswanathan ◽

M. Sai Baba ◽

A. Rai ◽

...

Keyword(s):

Andhra Pradesh ◽

Mineral Chemistry ◽

Unit Cell ◽

Geochemical Data ◽

Data Card ◽

Cuddapah Basin ◽

X Ray ◽

Cell Parameters ◽

X Ray Crystallography ◽

Lree Content

AbstractThe authors report the results of X-ray diffraction (XRD) and geochemical studies on bastnaesites (lanthanum cerium fluoro-carbonate) hosted in alkali Kanigiri Granite of the Prakasam district in Andhra Pradesh, India. The XRD pattern of the investigated bastnaesite displays sharply-defined reflections. The observed d-spacings of the bastnaesite are in very close agreement with those published for bastnaesite standard in International Centre for Diffraction Data (ICDD) Card No. 11–340. The calculated unit cell parameters (a o; c o) and unit cell volume (V) of the studied bastnaesite (a o 7.1301–7.1413 Å, c o 9.7643–9.7902Å and V 429.8940–432.3875 Å3) are almost equal to values published for bastnaesite standard (c o 7.1290 Å, c o 9.7744 Å and V 430.19 Å3) in the relevant data card.Geochemical data of bastnaesite reveals high content of Ce (mean 27.22%) followed by La (mean 16.82%), Nd (mean 6.12%) and Pr (mean 1.91%). Compared to light REE (LREE) content (mean 437165 ppm), heavy REE (HREE) content (mean 5867 ppm) is drastically low, with unusually high LREE/HREE ratio (mean 80). The chondrite-normalised plot also exhibits drastic enrichment of LREE relative to HREE with pronounced negative Euanomaly (mean Eu/Eu* = 0.15). High (LREE)N / (HREE)N, (La/Lu)N, (La/Yb)N and (Ce/Yb)N ratios reveal higher fractionation of LREE relative to HREE. The rare earth element (REE) contents of the studied bastnaesite are very close to REE contents of bastnaesite hosted in alkali syenite from Madagascar. The presence of bastnaesite in Kanigiri Granite and soils derived from it enhances the scope of further exploration for bastnaesite in several bodies of alkaline rocks and alkali granitoids present along the eastern margins of the Cuddapah basin, Andhra Pradesh.

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