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Teaching Documents by Rudra Mohan Pradhan

By the end of this unit you will be able to: By the end of this unit you will be able to:

Any linear feature, ± primary or secondary, that occurs ± penetratively (at the outcrop and/or ha... more Any linear feature, ± primary or secondary, that occurs ± penetratively (at the outcrop and/or hand specimen scale) and ± homogeneously in a body of rock If lineation is not penetrative and is present only along a discrete surface, then the ± lineation is surficial and is called a surface lineation Examples: slickenside striations defined by the alignment of mineral fibers or grooves sedimentary groove casts in a bedding plane flute casts and other linear primary structures on bedding of a turbidite

Any closely-spaced, systematically oriented planar feature that occurs penetratively in a body of... more Any closely-spaced, systematically oriented planar feature that occurs penetratively in a body of rock, and commonly associated with folds.

Papers by Rudra Mohan Pradhan

AGU Fall Meeting Abstracts, Dec 1, 2019

Goldschmidt2022 abstracts

Water

Despite being a biodiversity hotspot, the Mahanadi delta is facing groundwater salinization as on... more Despite being a biodiversity hotspot, the Mahanadi delta is facing groundwater salinization as one of the main environmental threats in the recent past. Hence, this study attempts to understand the dynamics of groundwater and its sustainable management options through numerical simulation in the Jagatsinghpur deltaic region. The result shows that groundwater in the study area is extensively abstracted for agricultural activities, which also causes the depletion of groundwater levels. The hydraulic head value varies from 0.7 to 15 m above mean sea level (MSL) with an average head of 6 m in this low-lying coastal region. The horizontal hydraulic conductivity and the specific yield values in the area are found to vary from 40 to 45 m/day and 0.05 to 0.07, respectively. The study area has been calibrated for two years (2004–2005) by using these parameters, followed by the validation of four years (2006–2009). The calibrated numerical model is used to evaluate the net recharge and ground...

Earth-Science Reviews

Pan-African orogeny that gave rise to Columbia and Gondwanaland Supercontinent assembly. The Gren... more Pan-African orogeny that gave rise to Columbia and Gondwanaland Supercontinent assembly. The Grenville orogeny has experienced thermal rejuvenation in the Aravalli and Bhilwara terranes.

Scientific Reports

Crystalline basement rock aquifers underlie more than 20% of the earth’s surface. However, owing ... more Crystalline basement rock aquifers underlie more than 20% of the earth’s surface. However, owing to an inadequate understanding of geological structures, it is challenging to locate the groundwater resources in crystalline hard rock terranes. In these terranes, faults, fractures, and shear zones play an important role in bedrock weathering and ultimately groundwater storage. This study integrates important geological structures with 2D high-resolution subsurface resistivity images in understanding the factors that influenced bedrock weathering and groundwater. The results reveal the variability of weathered zone depth in different structural zones (Zone-I to Zone-IV). This is due to the presence of foliations, fractures, and faults. A thicker weathered zone develops when a fracture/fault overprints a pre-existing planar pervasive structure like foliations (Zone-II) as compared to zones only with faults/fractures (Zone-III). Further, the transmissivity of boreholes also shows relativ...

New Prospects in Environmental Geosciences and Hydrogeosciences, 2022

Hydrological Sciences Journal, 2021

ABSTRACT In North Gujarat, local communities depend on the Precambrian basement aquifers for thei... more ABSTRACT In North Gujarat, local communities depend on the Precambrian basement aquifers for their primary source of water supply. The increasing demand for potable water puts stress on exploring for groundwater from less reliable sources of basement rocks. The main objective is to map groundwater potential zones (GWPZs) in water-scarce Precambrian terranes using integrated multi-criteria analysis (analytical hierarchy process and geospatial techniques). The output of the GWPZ map was grouped into six different categories. The results show that very high and high groundwater potentials extend over areas of 4.29% and 12.86%, respectively. The kappa index method was used for validation and showed an effective result between collected water-level data with calculated GWPZ. It shows 83.3% accuracy for very high, 85.7% for high and 90.1% for moderate GWPZs. The study shows promise and highlights that such an integrated analysis is reliable and can be applied anywhere with a similar set-up for groundwater prospecting and management.

Proceedings of the International Association of Hydrological Sciences, 2018

Fluoride is one of the critical ions that influence the groundwater quality. World Health Organiz... more Fluoride is one of the critical ions that influence the groundwater quality. World Health Organization (WHO, 1970) and Bureau of Indian Standards (BIS, 1991) set an upper limit of 1.5 mg L −1 in F − concentration for drinking water purpose and above affects teeth and bones of humans. The presence of fluoride in groundwater is due to an interaction of groundwater and fluoride bearing rocks. Fluoride rich groundwater is well known in granitic aquifers in India and elsewhere. Generally, the concentration of F − in groundwater is controlled by local geological setting; leaching and weathering of bedrock and climatic condition of an area. The main objective of the present study is to assess the hydrogeochemistry of groundwater and to understand the abundance of F − in groundwater in hard rock terranes of Ambaji region, North Gujarat. A total of forty-three representative groundwater samples were collected and analyzed for major cations and anions using ICP-AES, Ion Chromatograph (Metrohm 883 Basic IC Plus) and titration methods. The F − concentration in groundwater of this study area ranges from 0.17 to 2.7 mg L −1. Among, twenty groundwater samples have fluoride exceeding the maximum permissible limit as per the BIS (1.5 mg L −1). It is also noticed that residents of this region are affected by dental fluorosis. The general order of the dominance of major cations and anions are Ca 2+ > Mg 2+ > Na + > K + and HCO − 3 > Cl − > F − respectively. Geochemical classification of groundwater shows most of the samples are the alkaline earth-bicarbonate type. The semi-arid climatic conditions of the region, the dominance of granitoidgranulite suite rocks and the fracture network in the disturbed and brittle zone has facilitated the development of potential aquifers and enrichment in F − concentration in this area. The concentration of fluoride is due to high evaporation rate, longer residence time in the aquifer zone, intensive and long term pumping for irrigation. Edited by: Wenchao Sun Reviewed by: two anonymous referees

Water

Considering water as a limiting factor for socio-economic development, especially in arid/semi-ar... more Considering water as a limiting factor for socio-economic development, especially in arid/semi-arid regions, both scientific communities and policymakers are interested in groundwater recharge-related data. India is fast moving toward a crisis of groundwater due to intense abstraction and contamination. There is a lack of understanding regarding the occurrence, movement, and behaviors of groundwater in a fractured basement terrane. Therefore, integrated environmental isotopes (δ18O, δ2H, and 3H) and hydrogeochemical studies have been used to understand the recharge processes and geochemical evolution of groundwater in the fractured basement terranes of Gujarat, NW India. Our results show that the relative abundance of major cations and anions in the study basin are Ca2+ > Na+ > Mg2+ > K+ and HCO3− > Cl− > SO42− > NO3−, respectively. This suggests that the chemical weathering of silicate minerals influences the groundwater chemistry in the aquifer system. A change i...

By the end of this unit you will be able to: By the end of this unit you will be able to:

Any linear feature, ± primary or secondary, that occurs ± penetratively (at the outcrop and/or ha... more Any linear feature, ± primary or secondary, that occurs ± penetratively (at the outcrop and/or hand specimen scale) and ± homogeneously in a body of rock If lineation is not penetrative and is present only along a discrete surface, then the ± lineation is surficial and is called a surface lineation Examples: slickenside striations defined by the alignment of mineral fibers or grooves sedimentary groove casts in a bedding plane flute casts and other linear primary structures on bedding of a turbidite

Any closely-spaced, systematically oriented planar feature that occurs penetratively in a body of... more Any closely-spaced, systematically oriented planar feature that occurs penetratively in a body of rock, and commonly associated with folds.

AGU Fall Meeting Abstracts, Dec 1, 2019

Goldschmidt2022 abstracts

Water

Despite being a biodiversity hotspot, the Mahanadi delta is facing groundwater salinization as on... more Despite being a biodiversity hotspot, the Mahanadi delta is facing groundwater salinization as one of the main environmental threats in the recent past. Hence, this study attempts to understand the dynamics of groundwater and its sustainable management options through numerical simulation in the Jagatsinghpur deltaic region. The result shows that groundwater in the study area is extensively abstracted for agricultural activities, which also causes the depletion of groundwater levels. The hydraulic head value varies from 0.7 to 15 m above mean sea level (MSL) with an average head of 6 m in this low-lying coastal region. The horizontal hydraulic conductivity and the specific yield values in the area are found to vary from 40 to 45 m/day and 0.05 to 0.07, respectively. The study area has been calibrated for two years (2004–2005) by using these parameters, followed by the validation of four years (2006–2009). The calibrated numerical model is used to evaluate the net recharge and ground...

Earth-Science Reviews

Pan-African orogeny that gave rise to Columbia and Gondwanaland Supercontinent assembly. The Gren... more Pan-African orogeny that gave rise to Columbia and Gondwanaland Supercontinent assembly. The Grenville orogeny has experienced thermal rejuvenation in the Aravalli and Bhilwara terranes.

Scientific Reports

Crystalline basement rock aquifers underlie more than 20% of the earth’s surface. However, owing ... more Crystalline basement rock aquifers underlie more than 20% of the earth’s surface. However, owing to an inadequate understanding of geological structures, it is challenging to locate the groundwater resources in crystalline hard rock terranes. In these terranes, faults, fractures, and shear zones play an important role in bedrock weathering and ultimately groundwater storage. This study integrates important geological structures with 2D high-resolution subsurface resistivity images in understanding the factors that influenced bedrock weathering and groundwater. The results reveal the variability of weathered zone depth in different structural zones (Zone-I to Zone-IV). This is due to the presence of foliations, fractures, and faults. A thicker weathered zone develops when a fracture/fault overprints a pre-existing planar pervasive structure like foliations (Zone-II) as compared to zones only with faults/fractures (Zone-III). Further, the transmissivity of boreholes also shows relativ...

New Prospects in Environmental Geosciences and Hydrogeosciences, 2022

Hydrological Sciences Journal, 2021

ABSTRACT In North Gujarat, local communities depend on the Precambrian basement aquifers for thei... more ABSTRACT In North Gujarat, local communities depend on the Precambrian basement aquifers for their primary source of water supply. The increasing demand for potable water puts stress on exploring for groundwater from less reliable sources of basement rocks. The main objective is to map groundwater potential zones (GWPZs) in water-scarce Precambrian terranes using integrated multi-criteria analysis (analytical hierarchy process and geospatial techniques). The output of the GWPZ map was grouped into six different categories. The results show that very high and high groundwater potentials extend over areas of 4.29% and 12.86%, respectively. The kappa index method was used for validation and showed an effective result between collected water-level data with calculated GWPZ. It shows 83.3% accuracy for very high, 85.7% for high and 90.1% for moderate GWPZs. The study shows promise and highlights that such an integrated analysis is reliable and can be applied anywhere with a similar set-up for groundwater prospecting and management.

Proceedings of the International Association of Hydrological Sciences, 2018

Fluoride is one of the critical ions that influence the groundwater quality. World Health Organiz... more Fluoride is one of the critical ions that influence the groundwater quality. World Health Organization (WHO, 1970) and Bureau of Indian Standards (BIS, 1991) set an upper limit of 1.5 mg L −1 in F − concentration for drinking water purpose and above affects teeth and bones of humans. The presence of fluoride in groundwater is due to an interaction of groundwater and fluoride bearing rocks. Fluoride rich groundwater is well known in granitic aquifers in India and elsewhere. Generally, the concentration of F − in groundwater is controlled by local geological setting; leaching and weathering of bedrock and climatic condition of an area. The main objective of the present study is to assess the hydrogeochemistry of groundwater and to understand the abundance of F − in groundwater in hard rock terranes of Ambaji region, North Gujarat. A total of forty-three representative groundwater samples were collected and analyzed for major cations and anions using ICP-AES, Ion Chromatograph (Metrohm 883 Basic IC Plus) and titration methods. The F − concentration in groundwater of this study area ranges from 0.17 to 2.7 mg L −1. Among, twenty groundwater samples have fluoride exceeding the maximum permissible limit as per the BIS (1.5 mg L −1). It is also noticed that residents of this region are affected by dental fluorosis. The general order of the dominance of major cations and anions are Ca 2+ > Mg 2+ > Na + > K + and HCO − 3 > Cl − > F − respectively. Geochemical classification of groundwater shows most of the samples are the alkaline earth-bicarbonate type. The semi-arid climatic conditions of the region, the dominance of granitoidgranulite suite rocks and the fracture network in the disturbed and brittle zone has facilitated the development of potential aquifers and enrichment in F − concentration in this area. The concentration of fluoride is due to high evaporation rate, longer residence time in the aquifer zone, intensive and long term pumping for irrigation. Edited by: Wenchao Sun Reviewed by: two anonymous referees

Water

Considering water as a limiting factor for socio-economic development, especially in arid/semi-ar... more Considering water as a limiting factor for socio-economic development, especially in arid/semi-arid regions, both scientific communities and policymakers are interested in groundwater recharge-related data. India is fast moving toward a crisis of groundwater due to intense abstraction and contamination. There is a lack of understanding regarding the occurrence, movement, and behaviors of groundwater in a fractured basement terrane. Therefore, integrated environmental isotopes (δ18O, δ2H, and 3H) and hydrogeochemical studies have been used to understand the recharge processes and geochemical evolution of groundwater in the fractured basement terranes of Gujarat, NW India. Our results show that the relative abundance of major cations and anions in the study basin are Ca2+ > Na+ > Mg2+ > K+ and HCO3− > Cl− > SO42− > NO3−, respectively. This suggests that the chemical weathering of silicate minerals influences the groundwater chemistry in the aquifer system. A change i...

Fluoride is one of the critical ions that influence the groundwater quality. World Health Organiz... more Fluoride is one of the critical ions that influence the groundwater quality. World Health Organization (WHO, 1970) and Bureau of Indian Standards (BIS, 1991) set an upper limit of 1.5 mg L −1 in F − concentration for drinking water purpose and above affects teeth and bones of humans. The presence of fluoride in groundwater is due to an interaction of groundwater and fluoride bearing rocks. Fluoride rich groundwater is well known in granitic aquifers in India and elsewhere. Generally, the concentration of F − in groundwater is controlled by local geological setting; leaching and weathering of bedrock and climatic condition of an area. The main objective of the present study is to assess the hydrogeochemistry of groundwater and to understand the abundance of F − in groundwater in hard rock terranes of Ambaji region, North Gujarat. A total of forty-three representative groundwater samples were collected and analyzed for major cations and anions using ICP-AES, Ion Chromatograph (Metrohm 883 Basic IC Plus) and titration methods. The F − concentration in groundwater of this study area ranges from 0.17 to 2.7 mg L −1. Among, twenty groundwater samples have fluoride exceeding the maximum permissible limit as per the BIS (1.5 mg L −1). It is also noticed that residents of this region are affected by dental fluorosis. The general order of the dominance of major cations and anions are Ca 2+ > Mg 2+ > Na + > K + and HCO − 3 > Cl − > F − respectively. Geochemical classification of groundwater shows most of the samples are the alkaline earth-bicarbonate type. The semi-arid climatic conditions of the region, the dominance of granitoid-granulite suite rocks and the fracture network in the disturbed and brittle zone has facilitated the development of potential aquifers and enrichment in F − concentration in this area. The concentration of fluoride is due to high evaporation rate, longer residence time in the aquifer zone, intensive and long term pumping for irrigation.

Geomorphic evolution of any foreland basin is mainly controlled by spatial and temporal occurrenc... more Geomorphic evolution of any foreland basin is mainly controlled by spatial and temporal occurrence of tectonism and sediment inflow into it. The Indo-Gangetic foreland basin, bordered by the Himalayas witnesses rapid changes in geomorphology and sedimentation processes due to frequent subsidence and upliftment of the fault bounded tectonic blocks. The fluvial geomorphology of the basin is greatly controlled by this neotectonic process.

Earth-Science Reviews, 2015

ABSTRACT Study of spatial and temporal distribution of Holocene terminal/inland fans in the Indo-... more ABSTRACT Study of spatial and temporal distribution of Holocene terminal/inland fans in the Indo-Gangetic foreland basin suggests the segmentation of the basin was initiated at 9.3 Ka and continued up to 0.75 Ka in three distinct episodes. The earliest episode (9.3-7.3 Ka) was exclusively confined in the upper Gangetic plain. This episode covers 29% of total time span and contributes 13% of total faults including their reactivations. Development of six faults associated with terminal fans having large age gaps indicate relatively slow rate of faulting activities in the early Holocene. The second faulting episode was started at 6.4 Ka and continued up to 2.3 Ka covering 60% time of the total time span and contributed 69% of total faults (including their reactivations). Though in most of the time the faulting events were confined in the upper Gangetic plain, but development of few faults in the middle Gangetic plain in the middle of this episode shows a transitional shift of tectonic front from the upper to the middle Gangetic plain. The third faulting episode (1.5 -0.75 Ka) is mainly confined in the middle Gangetic plain. This episode covers 11% time of the total time span and contributes 18% of faults. Out of the eight faults, seven of them are in the middle Gangetic plains. Though these three episodes have contributed in segmentation of the Gangetic plains, but the second episode was responsible for major segmentation of the region. Two major tectonically stable periods (7.3-6.4 Ka and 2.3-1.5 Ka) and three minor periods (in duration of 0.5 Ka) have been observed in the region. Episodic development of faults in individual tectonic blocks indicates the stress distribution along the plains is non-uniform which can also be correlated to the adjacent corresponding segments of the Himalayan tectonics. It has been observed that, in each fault-bounded block the faulting events start slowly and later becomes more frequent. Previous work pointed out four tectonically active episodes between the Ghaghara and Kosi rivers with the oldest faulting event at 7.89 Ka. However, the region west of it (i.e. between the Ghaghara and Ghaggar rivers which includes rest of the upper Gangetic plain) shows neotectonic activities are earlier than 7.89 Ka (the oldest faulting event observed by previous study). The youngest faulting episode of the present study coincides with that of previous study and suggests the region between the Gandak and Kosi rivers is tectonically most active at present. The tectonically stable periods pointed out in the previous study between the Ghaghara-Kosi region is occupied by the faulting events in the upper Gangetic plains. Hence, instead of four tectonically active episodes, the whole Ganga plain witnesses three segmentation episodes with two major intervening stable periods. The change of orientation of the faults in the plain may be correlated to directional change of Indian plate motion, differential convergence, and upliftment rates along the Himalayan front and the spatial extension of subsurface Precambrian basement ridges into the plains.