Skip to main content

Dhananjay Sant

Maharaja Sayajirao University of Baroda, Department of Geology, Faculty Member

Followers

81

Following

42

Co-author

1

Public Views

Phone: +91265 2785560 ; +91 9426721620
Address: Department of Geology, Faculty of Science,
The Maharaja Sayajirao University of Baroda
Vadodara

less

PRABHIN SUKUMARAN

CHAROTAR UNIVERSITY OF SCIENCE AND TECHNOLOGY-CHANGA

The M.S.University Of Baroda-Vadodara

Wadia Institute Of Himalayan Geology

Deepak M Maurya

Pradeep Srivastava

falguni bhattacharya

Institute of Seismologic Research

Thakur Biswajeet

BSIP

InterestsView All (23)

Uploads

Papers by Dhananjay Sant

Multi-Proxy Records of Late Holocene Flood Events From the Lower Reaches of the Narmada River, Western India

Frontiers in Earth Science, 2021

Analyses of a fluvial sedimentary sequence from the lower reaches of the Narmada River establish ... more Analyses of a fluvial sedimentary sequence from the lower reaches of the Narmada River establish a record of rhythmic cycles of sediment facies that represent floods during the late Holocene. The south-west Indian monsoon strongly influences the study area, and heavy rainfall or cyclones which originate from either the Bay of Bengal or the Arabian Sea, also affect the region. Optically stimulated luminescence dating places the 8 m thick sediment sequence in the climate transition phase which ranges from the Medieval Warm Period to the Little Ice Age. Multi-proxy analyses including high-resolution granulometry, magnetic susceptibility, ferromagnetic mineral concentration, facies major oxide geochemistry, and micro-fossil records (from two sedimentary units) are used to study these late Holocene flood events. The latter are characterised by multiple sediment facies, depositional events, changes in channel morphology, and distinctive flood signatures. Integration of these records enabl...

High resolution facies record on late Holocene flood plain sediments from lower reaches of Narmada Valley, Western India

Journal of the Geological Society of India, 2012

A high resolution quantitative granulometric record for site Uchediya [21°43'2.22" N, 73° 6'26.22... more A high resolution quantitative granulometric record for site Uchediya [21°43'2.22" N, 73° 6'26.22" E; 10 m a. s. l.] gives understanding towards accretion history of the late Holocene flood plain in the lower reaches of Narmada River. Two sediment facies (sandy and muddy) and seven subfacies (sandy subfacies: St MS+FS+CS , Sm FS+MS , Sl FS+VFS , and St MS + CS ; muddy subfacies: Fm SILT+VFS+FS, Fm SILT+VFS+FS (O) and Fm SILT+VFS+FS (T)) are identified based on cluster analysis supplemented with sedimentary structures observed in field and other laboratory data. Changes in hydrodynamics are further deduced based on various sedimentological parameters and their ratios leading to arrive at a depositional model.

Linkage of paraglacial processes from last glacial to recent inferred from Spituk sequence, Leh valley, Ladakh Himalaya

Journal of the Geological Society of India, 2011

Abstract The paraglacial sequence in the Leh valley, Ladakh Himalaya preserves imprints of variou... more

Characterization of flood plain and climate change using multi-proxy records from the Mahi River Basin, Mainland Gujarat

J. Ind. Geophys. Union ( …, 2004

... Mahi and Sabarmati have led to significant progress in understanding various features ofQuate... more

www.elsevier.com/locate/chaos Fractal dimensional analysis of Indian climatic dynamics

In this paper, we use fractal dimensional analysis to investigate the Indian climatic dynamics. W... more In this paper, we use fractal dimensional analysis to investigate the Indian climatic dynamics. We analyze time series data of three major dynamic components of the climate––temperature, pressure and precipitation. We study how climate variability changes from month to month and from one season to the other. We also investigate variability both at a local level (for individual stations) and at a regional level (for groups of stations). Our studies suggest that regional climatic models typically would not be able to predict local climate since they deal with averaged quantities. We find an interesting effect that precipitation during the south-west monsoon is affected by temperature and pressure variability during the preceding winter. Ó 2003 Elsevier Ltd. All rights reserved. 1.

Geology and Structure of the Area Around Naswadi With Special Reference to Bagh Bed Exposures, Baroda District, Gujarat

Geologically the area around Naswadi comprises Precambrian metamorphics and granite, Bagh Beds an... more Geologically the area around Naswadi comprises Precambrian metamorphics and granite, Bagh Beds and Deccan Traps. The various formations have been dislocated at several places owing to tectonic movements along the Narmada Rift Zone. Most of the fau1ts lie parallel to the main Narmada lineament, e.g., ENE-WSW, and they have been further dislocated by NW-SE fractures.

Group Discussion on 'Drainage Evolution of Northwestern India with Special Reference to the Lost Sarasvati

Journal of Geological Society of India, 1998

Interest in gas hydrate began in 1970 when it was identified in bore holes intersecting oceanic s... more Interest in gas hydrate began in 1970 when it was identified in bore holes intersecting oceanic sediments along continental margins and at polar continental settings and its characteristic responses to seismic reflection prQfiles and oil-well electric logs. Several regions of gas hydrate concentration have been identified in the offshore region between New Jersey and Georgia and Alaska in USA and in Siberia and Norway. Deep hydrocarbon exploration has been initiated by several countries and drilling to confirm the existence oflarge quantities of gas seriously attempted. Information gathered is exchanged between oil companies and academic institutions. We are not sure whether any gas hydrate has been identified by ONGC. Since hydrates are stated to have a strong effect on acoustic reflections, seismic reflection profiles should be able to locate concentrations of hydrate over large areas. It is stated that gas hydrates are indicated by an anomalous seismic reflector known as the Bott...

Multi-Proxy Records of Late Holocene Flood Events From the Lower Reaches of the Narmada River, Western India

Front. Earth Sci.,, 2021

Analyses of a fluvial sedimentary sequence from the lower reaches of the Narmada River establish ... more Analyses of a fluvial sedimentary sequence from the lower reaches of the Narmada River establish a record of rhythmic cycles of sediment facies that represent floods during the late Holocene. The southwest Indian monsoon strongly influences the study area, and heavy rainfall or cyclones which originate from either the Bay of Bengal or the Arabian Sea, also affect the region. Optically stimulated luminescence dating places the 8 m thick sediment sequence in the climate transition phase which ranges from the Medieval Warm Period to the Little Ice Age. Multi-proxy analyses including high-resolution granulometry, magnetic susceptibility, ferromagnetic mineral concentration, facies major oxide geochemistry, and micro-fossil records (from two sedimentary units) are used to study these late Holocene flood events. The latter are characterised by multiple sediment facies, depositional events, changes in channel morphology, and distinctive flood signatures. Integration of these records enable...

Subsurface profiling of granite pluton using microtremor method: southern Aravalli, Gujarat, India

22 stations identified as the phyllite and quartzite boundary. The proposed equation describing f... more 22 stations identified as the phyllite and quartzite boundary. The proposed equation describing frequency–depth relationship between granite and overlaying regolith matches with those already published in the literature. The morphology of granite pluton highlights the rootless character of Champaner Group showing sharp discordance with granitic pluton. The findings of manifestation of pluton at a shallower depth imply a steep easterly plunge within the Champaner metasediments, whereas signature of pluton at a deeper level implies a gentle westerly plunge. The present method enables to assess how granite emplacement influences the surface structure. Abstract We report, using the microtremor method, a sub-surface granitic pluton underneath the Narukot Dome and in its western extension along a WNW profile, in proximity of eastern fringe of Cambay Rift, India. The dome and its extension is a part of the Champaner Group of rocks belonging to the Mesoproterozoic Aravalli Supergroup. The p...

Subsurface imaging of brown coal bearing Tertiary sedimentaries - Deccan Trap interface using microtremor method

Journal of Applied Geophysics

Subsurface profiling of granite pluton using microtremor method: southern Aravalli, Gujarat, India

International Journal of Earth Sciences

22 stations identified as the phyllite and quartzite boundary. The proposed equation describing f... more 22 stations identified as the phyllite and quartzite boundary. The proposed equation describing frequency–depth relationship between granite and overlaying regolith matches with those already published in the literature. The morphology of granite pluton highlights the rootless character of Champaner Group showing sharp discordance with granitic pluton. The findings of manifestation of pluton at a shallower depth imply a steep easterly plunge within the Champaner metasediments, whereas signature of pluton at a deeper level implies a gentle westerly plunge. The present method enables to assess how granite emplacement influences the surface structure. Abstract We report, using the microtremor method, a sub-surface granitic pluton underneath the Narukot Dome and in its western extension along a WNW profile, in proximity of eastern fringe of Cambay Rift, India. The dome and its extension is a part of the Champaner Group of rocks belonging to the Mesoproterozoic Aravalli Supergroup. The present finding elucidates development of an asym-metric double plunge along Narukot Dome. Microtremor measurements at 32 sites were carried out along the axial trace (N95°) of the dome. Fourier amplitude spectral studies were applied to obtain the ratio between the horizontal and vertical components of persisting Rayleigh waves as local ambient noise. Fundamental resonant frequencies with amplitude ≥1-sigma for each site are considered to distinguish rheological boundary. Two distinct rheological boundaries are identified based on frequency ranges determined in the terrain: (1) 0.2219–10.364 Hz recorded at 31 stations identified as the Champaner metasediment and granite boundary, and (2) 10.902–27.1119 Hz recorded at

Subsurface profiling along Banni Plains and bounding faults, Kachchh, Western India using microtremors method

Journal of Asian Earth Sciences

Keywords: Banni Plains, Kachchh Mainland Fault Microtremor Ambient noise Fundamental resonant fre... more Keywords: Banni Plains, Kachchh Mainland Fault Microtremor Ambient noise Fundamental resonant frequency H/V spectral ratio Positive flower structure A B S T R A C T The present article is a maiden attempt to map shallow subsurface rheological interfaces laterally across the Banni Plains and to decode geometry of the antecedent faults associated with the Kachchh Mainland Fault using the microtremor method. We conducted microtremor data acquisition for thirty-one sites along N-S transect from Loriya in Mainland Kachchh to Bhirandiara towards Patcham Island. Results from H/V spectral ratio technique show presence of two distinct rheological interfaces characterised by the resonant frequency (f r) ranges 0.23–0.27 Hz and 0.8252–1.5931 Hz respectively. The above frequency ranges are correlated with the depths of the Mesozoic-Basement (M-B) interface and the Quaternary-Tertiary (Q-T) interface. Using either the velocity (V s) of seismic waves at the M-B and Q-T interfaces (calculated as 1830 m/s and 411 m/s respectively) or the standard non-linear regression relationship derived for the Banni Plains (h = 110.18f r −1.97) we estimate the depth range for M-B interface to be 1442–1965 m and for Q-T interface to be 44–160 m. The subsurface profile across the Banni Plains educe cluster of four faults that develop an array of imbricate faults at the forefront of the Kachchh Mainland Fault within the Banni Footwall Syncline. The geometry of the faults suggests a &#39;positive flower structure&#39; indicating step-overs and strain restraining bends displaying push-ups resulting from localized shortening between converging bends of Kachchh Mainland Fault and the South Wagad Fault. The Banni Footwall Syncline preserves evidence of two episodes of deformations. The initial deformation event led to subsidence within the Kachchh Mainland Fault Zone bringing Mesozoic sequence juxtaposed to the basement rocks, whereas the later event is dominated by an uplift developing a positive flower structure in the Kachchh Mainland Fault Zone. Finally, the present study provides a mechanism to investigate faults and fault geometries correlating surface structural grains with subsurface structures.

Evidence of Human-Animal-Climate interaction in lower reaches of Narmada Valley, Western India

Recent explorations along the lower reaches of Narmada River in Western India revealed interestin... more Recent explorations along the lower reaches of Narmada River in Western India revealed interesting evidence regarding association of microliths with vertebrate fossils within the gravel lenses. These gravels occur as intercalated lenses within sand and silt facies. The gravel lenses form a part of a regional landform referred to as ‘palaeo-bank’, which comprises of Tertiary rocks towards eastern margin followed by gravel-sand-silt sequence in the middle reaches. On its further west, there occurs sandy-muddy facies. The palaeo-bank is of a regional 􀁏􀁅􀁃􀁊􀁅􀅂􀀿􀀽􀁊􀀿􀁁􀀃􀁐􀁄􀀽􀁐􀀃􀁁􀁔􀁐􀁁􀁊􀁀􀁏􀀃􀁂􀁋􀁎􀀃􀀽􀁈􀁉􀁋􀁏􀁐􀀃􀁏􀁅􀁔􀁐􀁕􀀃􀁇􀁅􀁈􀁋􀀃􀁉􀁁􀁐􀁁􀁎􀁏􀀃 laterally along the southern bank. The palaeo-bank is tentatively datable to the end phase of last glacial. The archaeological artefacts recovered from here included geometric and non-geometric tools, scrapers and cores. The vertebrate fragments included cattle bones, jaw fragments and tooth; fragments of elephant tusk; and fragments of rhino bones. The presence of these vertebrate rem...

The Quaternary evolution of Himalayan glaciation: Information from Anisotropy of Magnetic Susceptibility (AMS) studies on Spituk lake sediments, Leh valley, Ladhak Himalaya, India

ABSTRACT The Quaternary deposit of the Ladakh region of northwest Himalaya is although important ... more ABSTRACT The Quaternary deposit of the Ladakh region of northwest Himalaya is although important to evaluate the glaciations history in Kashmir valley, India, little information on this sequence is available till date. In this presentation, we focus on the 28 m thick sediment sequence of Spituk region (3407/50.25//N; 7731/28.30//E), Leh valley, Kashmir, to evaluate the changes in paleocurrent directions of glacial-derived water flows. The sequence consists of sand-dominated lower section up to ~13 m from base, followed by clay-dominated part in the rest of the sequence towards younging. Depending on the AMS data the total stratigraphic sequence can broadly be sub-divided into two parts. The section from the base up to the height of ~12 m shows both oblate and prolate shaped ellipsoids indicating a combination of lacustrine-cum-fluvial environment of deposition. The shape of AMS ellipsoids from the rest of the section between ~14 and 28 m is dominantly oblate suggesting for a predominant lacustrine environment with subordinate fluvial flow. The orientations of vertical to sub-vertical Kmin axes from the lower half of the section indicates a flow direction towards SE, in the upper lacustrine dominated environment the subordinate flow direction was oriented towards NE. The observed SE paleocurrent direction in the lower half of our studied sequence could indicate a major tectonic uplift in the NW during the deposition of this sequence. The NE flowing system in the upper part of the section indicates that the Zanskar range highland at the SW as the possible source area of our studied sedimentary sequence.

Late holocene storm records from lower reaches of Narmada valley, Western India

Journal of the Geological Society of India, 2012

A high resolution quantitative granulometric record for site Uchediya [21°43'2.22" N, 73° 6'26.22... more A high resolution quantitative granulometric record for site Uchediya [21°43'2.22" N, 73° 6'26.22" E; 10 m a. s. l.] gives understanding towards accretion history of the late Holocene flood plain in the lower reaches of Narmada River. Two sediment facies (sandy and muddy) and seven subfacies (sandy subfacies: St MS+FS+CS , Sm FS+MS , Sl FS+VFS , and St MS + CS ; muddy subfacies: Fm SILT+VFS+FS, Fm SILT+VFS (O) and Fm SILT+VFS (T)) are identified based on cluster analysis supplemented with sedimentary structures observed in field and other laboratory data. Changes in hydrodynamics are further deduced based on various sedimentological parameters and their ratios leading to arrive at a depositional model.

Drainage evolution of the lower Narmada valley, western India

Geomorphology, 1993

Various tectomc &sturbances from the Cretaceous to the present day have too&fled the geomorphlc f... more Various tectomc &sturbances from the Cretaceous to the present day have too&fled the geomorphlc features of western Indm Compression and extensional stresses generated by the northerly moving In&an plate, and its colhslon with the Eurasian plate, have brought about frequent changes m the drainage system and other features Different segments that he between several regional faults have encountered many upheavals and subsidences During the major part of the Tertmry the tributaries of the Narmada, Mahl and other westerly flowing rivers had much larger catchment areas that extended to the north The compresslonal stresses exerted during the Pllocene and Pleistocene epochs have shortened the basra of these ravers The release of stresses during the Early Pleistocene is mainly responsible for the development of the present highlands and lower surfaces Based on structural stu&es, subsurface data, se&mentatxon in different basins and the area of provenance and movement of the In&an plate, the authors have suggested successive stages of the landform development in the lower reaches of the Narmada valley 0169-555X/93/$06 00 © 1993 Elsevier Soence Pubhshers B V All rights reserved [~3 ALLUVIUH

Flood plain record of southwest Indian monsoon during the last glacial

Man and …, 2006

Rapid oscillations in the intensity of the Southwest Indian monsoon during the last glacial phase... more

A climate predictability index and its applications

Geophysical Research Letters, 1997

In this letter, a climate predictability index is proposed. It quantifies the predictability of t... more In this letter, a climate predictability index is proposed. It quantifies the predictability of three major components comprising the climate—temperature, pressure and precipitation. The quantification is done using a fractal dimensional analysis of the corresponding time series. The climate predictability index is calculated for 25 stations spread throughout India using the Global Historical Climatology Network dataset. Change in the index with the seasons suggests a strong influence of more than one climatic dynamics. In such cases, calculations done using mean yearly data are suspect. The index is shown to be useful in studying the interplay between various climatic components (viz. temperature, pressure and precipitation). Changes in predictability indices for temperature and pressure are seen to affect the index for precipitation. The index can be used as a discriminant for determining which stations are selected for use in developing regional climatic models.

Paleoclimatic data from 74KL and Guliya cores: New insights

Geophysical Research Letters, 2000

We analyze multi-proxy climatic records from the 74KL marine core and compare it with the δ 18 O ... more We analyze multi-proxy climatic records from the 74KL marine core and compare it with the δ 18 O record from the Guliya ice core. These records have important implications for the evolution of the Southwest Monsoon System. We observe three distinct climatic events (viz. 19 ka to 13.5 ka, 13.5 ka to 10 ka and 3.4 ka to present) from the last glacial phase to the present. Even though the first two events are well documented in the literature, our combined analysis of data from both the cores suggests alternative mechanisms which could have complemented and strengthened these events. The third, most recent event (occurring between 3.4 ka to present) does not seem to have been well documented earlier. We propose a possible mechanism to explain this event. We identify representative elements which better capture the above events as compared to more commonly used elements.

Onset of climate change at Last Glacial-Holocene transition: Role of the tropical Pacific

Multi-Proxy Records of Late Holocene Flood Events From the Lower Reaches of the Narmada River, Western India

Frontiers in Earth Science, 2021

Analyses of a fluvial sedimentary sequence from the lower reaches of the Narmada River establish ... more Analyses of a fluvial sedimentary sequence from the lower reaches of the Narmada River establish a record of rhythmic cycles of sediment facies that represent floods during the late Holocene. The south-west Indian monsoon strongly influences the study area, and heavy rainfall or cyclones which originate from either the Bay of Bengal or the Arabian Sea, also affect the region. Optically stimulated luminescence dating places the 8 m thick sediment sequence in the climate transition phase which ranges from the Medieval Warm Period to the Little Ice Age. Multi-proxy analyses including high-resolution granulometry, magnetic susceptibility, ferromagnetic mineral concentration, facies major oxide geochemistry, and micro-fossil records (from two sedimentary units) are used to study these late Holocene flood events. The latter are characterised by multiple sediment facies, depositional events, changes in channel morphology, and distinctive flood signatures. Integration of these records enabl...

High resolution facies record on late Holocene flood plain sediments from lower reaches of Narmada Valley, Western India

Journal of the Geological Society of India, 2012

A high resolution quantitative granulometric record for site Uchediya [21°43'2.22" N, 73° 6'26.22... more A high resolution quantitative granulometric record for site Uchediya [21°43'2.22" N, 73° 6'26.22" E; 10 m a. s. l.] gives understanding towards accretion history of the late Holocene flood plain in the lower reaches of Narmada River. Two sediment facies (sandy and muddy) and seven subfacies (sandy subfacies: St MS+FS+CS , Sm FS+MS , Sl FS+VFS , and St MS + CS ; muddy subfacies: Fm SILT+VFS+FS, Fm SILT+VFS+FS (O) and Fm SILT+VFS+FS (T)) are identified based on cluster analysis supplemented with sedimentary structures observed in field and other laboratory data. Changes in hydrodynamics are further deduced based on various sedimentological parameters and their ratios leading to arrive at a depositional model.

Linkage of paraglacial processes from last glacial to recent inferred from Spituk sequence, Leh valley, Ladakh Himalaya

Journal of the Geological Society of India, 2011

Abstract The paraglacial sequence in the Leh valley, Ladakh Himalaya preserves imprints of variou... more

Characterization of flood plain and climate change using multi-proxy records from the Mahi River Basin, Mainland Gujarat

J. Ind. Geophys. Union ( …, 2004

... Mahi and Sabarmati have led to significant progress in understanding various features ofQuate... more

www.elsevier.com/locate/chaos Fractal dimensional analysis of Indian climatic dynamics

In this paper, we use fractal dimensional analysis to investigate the Indian climatic dynamics. W... more In this paper, we use fractal dimensional analysis to investigate the Indian climatic dynamics. We analyze time series data of three major dynamic components of the climate––temperature, pressure and precipitation. We study how climate variability changes from month to month and from one season to the other. We also investigate variability both at a local level (for individual stations) and at a regional level (for groups of stations). Our studies suggest that regional climatic models typically would not be able to predict local climate since they deal with averaged quantities. We find an interesting effect that precipitation during the south-west monsoon is affected by temperature and pressure variability during the preceding winter. Ó 2003 Elsevier Ltd. All rights reserved. 1.

Geology and Structure of the Area Around Naswadi With Special Reference to Bagh Bed Exposures, Baroda District, Gujarat

Geologically the area around Naswadi comprises Precambrian metamorphics and granite, Bagh Beds an... more Geologically the area around Naswadi comprises Precambrian metamorphics and granite, Bagh Beds and Deccan Traps. The various formations have been dislocated at several places owing to tectonic movements along the Narmada Rift Zone. Most of the fau1ts lie parallel to the main Narmada lineament, e.g., ENE-WSW, and they have been further dislocated by NW-SE fractures.

Group Discussion on 'Drainage Evolution of Northwestern India with Special Reference to the Lost Sarasvati

Journal of Geological Society of India, 1998

Interest in gas hydrate began in 1970 when it was identified in bore holes intersecting oceanic s... more Interest in gas hydrate began in 1970 when it was identified in bore holes intersecting oceanic sediments along continental margins and at polar continental settings and its characteristic responses to seismic reflection prQfiles and oil-well electric logs. Several regions of gas hydrate concentration have been identified in the offshore region between New Jersey and Georgia and Alaska in USA and in Siberia and Norway. Deep hydrocarbon exploration has been initiated by several countries and drilling to confirm the existence oflarge quantities of gas seriously attempted. Information gathered is exchanged between oil companies and academic institutions. We are not sure whether any gas hydrate has been identified by ONGC. Since hydrates are stated to have a strong effect on acoustic reflections, seismic reflection profiles should be able to locate concentrations of hydrate over large areas. It is stated that gas hydrates are indicated by an anomalous seismic reflector known as the Bott...

Multi-Proxy Records of Late Holocene Flood Events From the Lower Reaches of the Narmada River, Western India

Front. Earth Sci.,, 2021

Analyses of a fluvial sedimentary sequence from the lower reaches of the Narmada River establish ... more Analyses of a fluvial sedimentary sequence from the lower reaches of the Narmada River establish a record of rhythmic cycles of sediment facies that represent floods during the late Holocene. The southwest Indian monsoon strongly influences the study area, and heavy rainfall or cyclones which originate from either the Bay of Bengal or the Arabian Sea, also affect the region. Optically stimulated luminescence dating places the 8 m thick sediment sequence in the climate transition phase which ranges from the Medieval Warm Period to the Little Ice Age. Multi-proxy analyses including high-resolution granulometry, magnetic susceptibility, ferromagnetic mineral concentration, facies major oxide geochemistry, and micro-fossil records (from two sedimentary units) are used to study these late Holocene flood events. The latter are characterised by multiple sediment facies, depositional events, changes in channel morphology, and distinctive flood signatures. Integration of these records enable...

Subsurface profiling of granite pluton using microtremor method: southern Aravalli, Gujarat, India

22 stations identified as the phyllite and quartzite boundary. The proposed equation describing f... more 22 stations identified as the phyllite and quartzite boundary. The proposed equation describing frequency–depth relationship between granite and overlaying regolith matches with those already published in the literature. The morphology of granite pluton highlights the rootless character of Champaner Group showing sharp discordance with granitic pluton. The findings of manifestation of pluton at a shallower depth imply a steep easterly plunge within the Champaner metasediments, whereas signature of pluton at a deeper level implies a gentle westerly plunge. The present method enables to assess how granite emplacement influences the surface structure. Abstract We report, using the microtremor method, a sub-surface granitic pluton underneath the Narukot Dome and in its western extension along a WNW profile, in proximity of eastern fringe of Cambay Rift, India. The dome and its extension is a part of the Champaner Group of rocks belonging to the Mesoproterozoic Aravalli Supergroup. The p...

Subsurface imaging of brown coal bearing Tertiary sedimentaries - Deccan Trap interface using microtremor method

Journal of Applied Geophysics

Subsurface profiling of granite pluton using microtremor method: southern Aravalli, Gujarat, India

International Journal of Earth Sciences

22 stations identified as the phyllite and quartzite boundary. The proposed equation describing f... more 22 stations identified as the phyllite and quartzite boundary. The proposed equation describing frequency–depth relationship between granite and overlaying regolith matches with those already published in the literature. The morphology of granite pluton highlights the rootless character of Champaner Group showing sharp discordance with granitic pluton. The findings of manifestation of pluton at a shallower depth imply a steep easterly plunge within the Champaner metasediments, whereas signature of pluton at a deeper level implies a gentle westerly plunge. The present method enables to assess how granite emplacement influences the surface structure. Abstract We report, using the microtremor method, a sub-surface granitic pluton underneath the Narukot Dome and in its western extension along a WNW profile, in proximity of eastern fringe of Cambay Rift, India. The dome and its extension is a part of the Champaner Group of rocks belonging to the Mesoproterozoic Aravalli Supergroup. The present finding elucidates development of an asym-metric double plunge along Narukot Dome. Microtremor measurements at 32 sites were carried out along the axial trace (N95°) of the dome. Fourier amplitude spectral studies were applied to obtain the ratio between the horizontal and vertical components of persisting Rayleigh waves as local ambient noise. Fundamental resonant frequencies with amplitude ≥1-sigma for each site are considered to distinguish rheological boundary. Two distinct rheological boundaries are identified based on frequency ranges determined in the terrain: (1) 0.2219–10.364 Hz recorded at 31 stations identified as the Champaner metasediment and granite boundary, and (2) 10.902–27.1119 Hz recorded at

Subsurface profiling along Banni Plains and bounding faults, Kachchh, Western India using microtremors method

Journal of Asian Earth Sciences

Keywords: Banni Plains, Kachchh Mainland Fault Microtremor Ambient noise Fundamental resonant fre... more Keywords: Banni Plains, Kachchh Mainland Fault Microtremor Ambient noise Fundamental resonant frequency H/V spectral ratio Positive flower structure A B S T R A C T The present article is a maiden attempt to map shallow subsurface rheological interfaces laterally across the Banni Plains and to decode geometry of the antecedent faults associated with the Kachchh Mainland Fault using the microtremor method. We conducted microtremor data acquisition for thirty-one sites along N-S transect from Loriya in Mainland Kachchh to Bhirandiara towards Patcham Island. Results from H/V spectral ratio technique show presence of two distinct rheological interfaces characterised by the resonant frequency (f r) ranges 0.23–0.27 Hz and 0.8252–1.5931 Hz respectively. The above frequency ranges are correlated with the depths of the Mesozoic-Basement (M-B) interface and the Quaternary-Tertiary (Q-T) interface. Using either the velocity (V s) of seismic waves at the M-B and Q-T interfaces (calculated as 1830 m/s and 411 m/s respectively) or the standard non-linear regression relationship derived for the Banni Plains (h = 110.18f r −1.97) we estimate the depth range for M-B interface to be 1442–1965 m and for Q-T interface to be 44–160 m. The subsurface profile across the Banni Plains educe cluster of four faults that develop an array of imbricate faults at the forefront of the Kachchh Mainland Fault within the Banni Footwall Syncline. The geometry of the faults suggests a &#39;positive flower structure&#39; indicating step-overs and strain restraining bends displaying push-ups resulting from localized shortening between converging bends of Kachchh Mainland Fault and the South Wagad Fault. The Banni Footwall Syncline preserves evidence of two episodes of deformations. The initial deformation event led to subsidence within the Kachchh Mainland Fault Zone bringing Mesozoic sequence juxtaposed to the basement rocks, whereas the later event is dominated by an uplift developing a positive flower structure in the Kachchh Mainland Fault Zone. Finally, the present study provides a mechanism to investigate faults and fault geometries correlating surface structural grains with subsurface structures.

Evidence of Human-Animal-Climate interaction in lower reaches of Narmada Valley, Western India

Recent explorations along the lower reaches of Narmada River in Western India revealed interestin... more Recent explorations along the lower reaches of Narmada River in Western India revealed interesting evidence regarding association of microliths with vertebrate fossils within the gravel lenses. These gravels occur as intercalated lenses within sand and silt facies. The gravel lenses form a part of a regional landform referred to as ‘palaeo-bank’, which comprises of Tertiary rocks towards eastern margin followed by gravel-sand-silt sequence in the middle reaches. On its further west, there occurs sandy-muddy facies. The palaeo-bank is of a regional 􀁏􀁅􀁃􀁊􀁅􀅂􀀿􀀽􀁊􀀿􀁁􀀃􀁐􀁄􀀽􀁐􀀃􀁁􀁔􀁐􀁁􀁊􀁀􀁏􀀃􀁂􀁋􀁎􀀃􀀽􀁈􀁉􀁋􀁏􀁐􀀃􀁏􀁅􀁔􀁐􀁕􀀃􀁇􀁅􀁈􀁋􀀃􀁉􀁁􀁐􀁁􀁎􀁏􀀃 laterally along the southern bank. The palaeo-bank is tentatively datable to the end phase of last glacial. The archaeological artefacts recovered from here included geometric and non-geometric tools, scrapers and cores. The vertebrate fragments included cattle bones, jaw fragments and tooth; fragments of elephant tusk; and fragments of rhino bones. The presence of these vertebrate rem...

The Quaternary evolution of Himalayan glaciation: Information from Anisotropy of Magnetic Susceptibility (AMS) studies on Spituk lake sediments, Leh valley, Ladhak Himalaya, India

ABSTRACT The Quaternary deposit of the Ladakh region of northwest Himalaya is although important ... more ABSTRACT The Quaternary deposit of the Ladakh region of northwest Himalaya is although important to evaluate the glaciations history in Kashmir valley, India, little information on this sequence is available till date. In this presentation, we focus on the 28 m thick sediment sequence of Spituk region (3407/50.25//N; 7731/28.30//E), Leh valley, Kashmir, to evaluate the changes in paleocurrent directions of glacial-derived water flows. The sequence consists of sand-dominated lower section up to ~13 m from base, followed by clay-dominated part in the rest of the sequence towards younging. Depending on the AMS data the total stratigraphic sequence can broadly be sub-divided into two parts. The section from the base up to the height of ~12 m shows both oblate and prolate shaped ellipsoids indicating a combination of lacustrine-cum-fluvial environment of deposition. The shape of AMS ellipsoids from the rest of the section between ~14 and 28 m is dominantly oblate suggesting for a predominant lacustrine environment with subordinate fluvial flow. The orientations of vertical to sub-vertical Kmin axes from the lower half of the section indicates a flow direction towards SE, in the upper lacustrine dominated environment the subordinate flow direction was oriented towards NE. The observed SE paleocurrent direction in the lower half of our studied sequence could indicate a major tectonic uplift in the NW during the deposition of this sequence. The NE flowing system in the upper part of the section indicates that the Zanskar range highland at the SW as the possible source area of our studied sedimentary sequence.

Late holocene storm records from lower reaches of Narmada valley, Western India

Journal of the Geological Society of India, 2012

A high resolution quantitative granulometric record for site Uchediya [21°43'2.22" N, 73° 6'26.22... more A high resolution quantitative granulometric record for site Uchediya [21°43'2.22" N, 73° 6'26.22" E; 10 m a. s. l.] gives understanding towards accretion history of the late Holocene flood plain in the lower reaches of Narmada River. Two sediment facies (sandy and muddy) and seven subfacies (sandy subfacies: St MS+FS+CS , Sm FS+MS , Sl FS+VFS , and St MS + CS ; muddy subfacies: Fm SILT+VFS+FS, Fm SILT+VFS (O) and Fm SILT+VFS (T)) are identified based on cluster analysis supplemented with sedimentary structures observed in field and other laboratory data. Changes in hydrodynamics are further deduced based on various sedimentological parameters and their ratios leading to arrive at a depositional model.

Drainage evolution of the lower Narmada valley, western India

Geomorphology, 1993

Various tectomc &sturbances from the Cretaceous to the present day have too&fled the geomorphlc f... more Various tectomc &sturbances from the Cretaceous to the present day have too&fled the geomorphlc features of western Indm Compression and extensional stresses generated by the northerly moving In&an plate, and its colhslon with the Eurasian plate, have brought about frequent changes m the drainage system and other features Different segments that he between several regional faults have encountered many upheavals and subsidences During the major part of the Tertmry the tributaries of the Narmada, Mahl and other westerly flowing rivers had much larger catchment areas that extended to the north The compresslonal stresses exerted during the Pllocene and Pleistocene epochs have shortened the basra of these ravers The release of stresses during the Early Pleistocene is mainly responsible for the development of the present highlands and lower surfaces Based on structural stu&es, subsurface data, se&mentatxon in different basins and the area of provenance and movement of the In&an plate, the authors have suggested successive stages of the landform development in the lower reaches of the Narmada valley 0169-555X/93/$06 00 © 1993 Elsevier Soence Pubhshers B V All rights reserved [~3 ALLUVIUH

Flood plain record of southwest Indian monsoon during the last glacial

Man and …, 2006

Rapid oscillations in the intensity of the Southwest Indian monsoon during the last glacial phase... more

A climate predictability index and its applications

Geophysical Research Letters, 1997

In this letter, a climate predictability index is proposed. It quantifies the predictability of t... more In this letter, a climate predictability index is proposed. It quantifies the predictability of three major components comprising the climate—temperature, pressure and precipitation. The quantification is done using a fractal dimensional analysis of the corresponding time series. The climate predictability index is calculated for 25 stations spread throughout India using the Global Historical Climatology Network dataset. Change in the index with the seasons suggests a strong influence of more than one climatic dynamics. In such cases, calculations done using mean yearly data are suspect. The index is shown to be useful in studying the interplay between various climatic components (viz. temperature, pressure and precipitation). Changes in predictability indices for temperature and pressure are seen to affect the index for precipitation. The index can be used as a discriminant for determining which stations are selected for use in developing regional climatic models.

Paleoclimatic data from 74KL and Guliya cores: New insights

Geophysical Research Letters, 2000

We analyze multi-proxy climatic records from the 74KL marine core and compare it with the δ 18 O ... more We analyze multi-proxy climatic records from the 74KL marine core and compare it with the δ 18 O record from the Guliya ice core. These records have important implications for the evolution of the Southwest Monsoon System. We observe three distinct climatic events (viz. 19 ka to 13.5 ka, 13.5 ka to 10 ka and 3.4 ka to present) from the last glacial phase to the present. Even though the first two events are well documented in the literature, our combined analysis of data from both the cores suggests alternative mechanisms which could have complemented and strengthened these events. The third, most recent event (occurring between 3.4 ka to present) does not seem to have been well documented earlier. We propose a possible mechanism to explain this event. We identify representative elements which better capture the above events as compared to more commonly used elements.

Onset of climate change at Last Glacial-Holocene transition: Role of the tropical Pacific