Study of physiochemical properties of groundwater in an area of 1000 sq km around Agra city, Uttar Pradesh, India was carried out to decipher the suitability of groundwater for irrigation. About 78% of the study area is utilized for agriculture and most of the crops are irrigated with tubewells (i.e. from groundwater sources). Therefore, it is important to study the quality and suitability of the groundwater for this purpose. Since the area falls under the Semi-arid zone, the average frequency of irrigation is high for the crops being harvested, the proper soil management is needed for sustainable agricultural development of the area. 

A total of 200 groundwater samples were collected (pre- and post-monsoon) from hand pumps, submersible pumps, and irrigation tubewells as per the availability on a grid pattern between the periods of June 2012 to February 2014. The samples were analyzed for major, traces and other physical properties of the water like pH, TDS, and electrical conductivity. To evaluate the quality of the groundwater different irrigational parameters like Electrical Conductivity (EC), Kelly’s Ratio, Sodium Adsorption Ratio (SAR) values, Magnesium Adsorption Ratio and Sodium Percentage were worked out. Wilcox diagram indicates that 18% of water samples fall in unsuitable class while 14% samples are in Doubtful to Unsuitable class while about 47% of samples are good to permissible for irrigation. USSL diagram shows that the majority of the samples fall in S1C3 (50.5%) and S2C4 (20.3%) and only 2.3% samples are falling in S1C2 Class with low alkali and medium salinity hazard. Therefore, the majority of the water sources are either unsuitable for irrigation or may be used with adequate management of drainage and salinity treatments. The Magnesium Adsorption Ration of the samples is even worse and more than 90% samples are failing this parameter for irrigation. 51% samples are showing Kelly’s ratio of >1, failing to qualify the standard for irrigation water. Doneen’s plot indicates that 39.3% of water samples are falling in Class-III field with <25% maximum permeability which is not suitable for irrigation in normal conditions.

Keywords: Groundwater quality, Irrigation, Sodium Absorption Ratio (SAR), Kelly’s Ratio, Wilcox diagram, USSL diagram, Agra

            The relative sea-level fall in terminal Cenozoic exposed continental shelf of Kutch provided opportunity to develop a fluvial system of braided nature. The terminal Cenozoic formation of Kutch, the Sandhan Formation provides a rare opportunity where a clear transition from a marine to fluvial succession can be identified in the field. The occurrence of fluvial deposits in the rock record suggest an abrupt and considerable fall in the base level. The ~157 m thick upper part of the Sandhan Formation is deposited in the fluvial environment. The fluvial succession of the Sandhan Formation has not been studied for their sediment geochemistry. Provenance, tectonic setting, paleo-weathering, and paleoclimate of the upper part of the Sandhan Formation is interpreted on the basis of extensive geochemical and petrographic analysis of sandstone samples by using XRF, the bivariate diagram Log (SiO₂/Al₂O₃) versus Log (Na₂O/K₂O) diagram, QFL diagram, Provenance Discrimination Plot, SiO₂/Al₂O₃ ratio with K₂O/Na₂O ratio, Chemical Index of Alteration (CIA) weathering indices, Plagioclase Index of Alteration (PIA), Chemical index of Weathering (CIW), A-CN-K Diagram, SiO₂/Al₂O₃ ratio and binary SiO₂ wt.% versus (Al₂O₃ + K₂O + Na₂O) wt.% diagram. These provided the detailed geological origin of the upper part of the Sandhan Formation as, it originated from a mixed provenance (quartzose sedimentary and mafic igneous), with arkose to subarkose nature. The upper part of Sandhan Formation is formed in an arid paleoclimate, both Active Continental Margin (ACM) and Passive Margin (PM) tectonic setting and moderate to intense paleo-weathering conditions.

Keywords: Sandhan Formation, Kutch, Siliciclastic Rocks, Sediment Geochemistry, Clastic Provenance, Tectonic Setting, Paleo-weathering, Paleoclimate

The pegmatites in the Neoproterozoic A-type granites of Nagamalai-Pudukottai area are of two types- gray and pink. These pegmatites contain hornblende.  In this work an attempt is made to understand the nature of magma, the process of crystallisation and the Pressure-Temperature (P-T) conditions of formation of the rock with the help of the Electron microprobe (EPMA) study of hornblende from both varieties of pegmatites.

The EPMA of the hornblende from the granitic pegmatites indicate their calcic nature. The structural formula of these calcic amphiboles corresponds to hastingsite. The Al^tot pressure calibration suggests the formation of the gray and pink pegmatites to be 5 kilobar (average). Based on the amphibole-plagioclase thermometer the magmatic temperature deduced for gray and pink pegmatites is 760^oC and 745^oC respectively. These temperature values suggest the later formation of pink pegmatites. The study reveals the formation of the granites and associated pegmatites from a less evolved, hydrous, and less viscous calcic melt in the upper crust.

Keywords: Granites, Granitic pegmatites, amphibole, geothermometry, geobarometry