Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

M. R. G. Sayyed ¹, A. M. Patwardhan ¹

Affiliations
1 Department of Geology, University of Poona, Pune 411 007, IN

Abstract

Upper Kamthi sandstones are distinct being unimodal, less feldspathic, texturally more mature with a dominant ferruginous cement when compared with the Lower and Middle Kamthi sandstones which are bimodal, feldspathic with abundant carbonate cement. The bimodality and textural inversion in the latter is attributed to their derivation from both metasedimentary and plutonic sources. This is also reflected in the erratic distribution of Al₂O₃ total iron and Na₂O contents. The Yerrapalli sandstones are petrographically not very different from the Lower and Middle Kamthi sandstones, but show finer grained feldspar, abundant carbonate cement and lime pellets. The Bhimaram sand'stones, however, show lesser carbonate content and are characterized by the presence of pyrite and ferruginous cement. In general, the Yerrapalli and Bhimaram sandstones show a greater mineralogical and textural maturity than the Lower and Middle Kamthi units. The distribution of CaO shows a maxima in. the middle portion of the Lower Maleri sequence, other major elements donot show any systematic variation.

Keywords

Gondwana Pranhita - Godavari Basin, Kamthi Maleri Fm.

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A. M. Patwardhan ¹

Affiliations
1 Professor of Geology, University of Poonu, Pune - 411 007, IN

Abstract

No Abstract.

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A. M. Patwardhan ¹, N. R. Karmalkar ¹, D. B. Panaskar ¹, D. C. Meshram ¹

Affiliations
1 Department of Geology, University of Poona, Pune - 411 007, IN

Abstract

The continued seismicity in the Koyna region has had the maximum impact in the Patan Taluka of the Satara District in Maharashtra within 30 km radius from the epicentral region of earthquakes. The Government of Maharashtra has undertaken rehabilitation of the villages which have suffered the damage and are threatened also by the collapsing edges of the overhanging lateritic cliffs. On the M.M. intensity scale the damages suffered by the settlements and lateritic plateau would indicate an intensity between VII and VIII. A high acceleration, maximum of 0.1 g (100 cm/sec²), is inferred for the soil profiles and alluvial tracts, loose gravel colluvium, river terraces material and weathered basalts on which the settlements are located. The continued seismicity around Koyna reservoir is often referred to as "reservoir induced", but such a mechanism is considered valid only for earthquakes originating from very shallow depths. For earthquakes whose hypocenters lie far below in the basement rocks (depth >3 km), the magnitude frequency relationship (26 years period) is similar to that observed in any tectonically active regions. It seems that the seismicity is related more to the reactivation of basement faults, reflected also in the overall geomorphological features of the region.

Keywords

Geomorphology, Seismicity, Satara District, Maharashtra.

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Masoud Masoudi ¹, A. M. Patwardhan ², S. D. Gore ³

Affiliations
1 Department of Desert Zones Management, Agricultural College, Shiraz University, IR
2 Interdiscrplinary School (Science), University of Pune, Potdar Sankul, Pune - 411 007, IN
3 Department of Statistics, University of Pune, Pune - 41 1007, IN

Abstract

Entire land of Southern Iran faces problems arising out of various types of land degradation of which lowering of groundwater table forms an important feature. The Qareh Aghaj sub basin, which covers the upper reaches of Mond River, has been chosen for a test assessment of the consequences of lowering of groundwater table. The various kinds of data gathered from the records and published reports of the Ministries of Agriculture and Energy of Iran have been analyzed in the GIS mode. The paper attempts at evolving a model for assessing the risk of lowering of groundwater table by considering eleven indicators of the same. The risk is related more to the irrigation activity which has led to increasing the number of wells, and groundwater overexploitation during the recent years, but some natural causes like the fluctuation in annual rainfall and hydrogeological characteristics also played a role in the recharge dynamics of the aquifers. The GIS analysis has made it possible to distinguish the areas with potential risk' from those widespread areas that showed the 'actual risk' of lowering of water table. It helped also to identify the areas which should be chosen on priority basis for remedial measures to mitigate the impact of lowering of groundwater table.

Keywords

Groundwater Table, GSI, Indicators, Actual Risk, Potentlal Risk, Qareh Aghaj Basin, Southern Iran

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Hassan Zamanian ¹, A. M. Patwardhan ¹

Affiliations
1 Department of Geology, PO Box 465 , Lorestan University, Khorram Abad, IR

Abstract

The Almoughlagh Batholith intruded during the Oligomiocene period the Triassic-Jurassic volcano-sedimentary sequence of the Songhor Series, occurring within the Sanandaz-Sirjan tectonic zone. The Baba Ali magnetite deposit is hosted by meta-dioritic rocks, the dioritic pluton intruded the Songhor Series earlier during the Late Kimmerian (-136Ma) orogeny. The Chenar deposit is much smaller and is hosted by metamorphosed carbonate rocks interbedded with the Upper Songhor Series. The intrusion of Almoughlagh Batholith skarnized the meta-diorite and the impure carbonate units and the associated hydrothermal activity was accompanied by magnetite mineralization. The Baba Ali deposit has been identified as a calcic Fe-skarn, while the Chenar deposit has characteristics of calcium-magnesium skarn. The batholith consists of rocks belonging chiefly to the quartz-syenite and syenogranite groups, which are low in modal quartz, metaluminous to peraluminous and calc-alkaline in composition. A descending temperature regime, beginning at the peak of thermal metamorphism (566°C) and ending with the main phase of magnetite mineralization (450-350°C) has been deduced.

Keywords

Calcic Fe-Skarn, Endo/Exo-Skarn, Zoning, Hydrothermal Magnetite, Island Arc Magmatism, Almoughlagh Batholith, Western Iran.

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