Volume 26(1) (2022),1-6
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Seismic Attribute Analysis of 3D seismic data: A case study from Taranaki basin, New Zealand
Pradeep Mahadasu* and Kumar Hemant Singh
Department of Earth Sciences, Indian Institute of Technology Bombay-400076.
ABSTRACT
Seismic attributes are the elements of seismic data that are extracted from the seismic reflection data to create seismic characteristics that emphasize certain physical, geological, or reservoir property aspects. Seismic characteristics derived from reflection data are based on a variety of physical processes. Wave properties, including amplitude, frequency, phase, and velocity, vary significantly when seismic waves propagate through earth’s strata. Because of their restricted horizontal and vertical distribution, traditional seismic interpretation cannot always anticipate the geometry and spatial distribution of structural and stratigraphical features. The quantitative interpretation through seismic attributes enables a unique use of seismic characteristics to understand better fault systems, paleochannels, and spatial reservoir distribution. Seismic attributes, such as coherence, local structural dip, curvature, sweetness, RMS attribute, and envelope, are effective tools to understand the detailed geometry and variation in structural and stratigraphical features. Comparative seismic attribute analysis is undertaken to understand better the geometries of structural and stratigraphic features using 3D marine seismic data from Parihaka (Taranaki basin, New Zealand). The results can significantly improve the structural and stratigraphical interpretation and exploration objectives.
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Comparison of improved particle swarm optimization with Marquardt Algorithm for simulation of sedimentary basin with parabolic density contrast using gravity data
Soudeh Loni and Mahmoud Mehramuz*
Department of Earth Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran
ABSTRACT
In this paper, Improved Particle Swarm Optimization (IPSO) and Marquardt algorithms are used to estimate the depth of the sedimentary basin, leading to the determination of the basement and simulation of sedimentary basin. In these methods, the sedimentary basin is simulated by using the density contrast that changes parabolically with depth and several prisms aligned with the same width and different lengths. The proficiency of the mentioned algorithms has been investigated by considering a hypothetical sedimentary basin. Depth estimation of the sedimentary basin using the calculated gravity field is performed by both mentioned methods and their results compared. By comparing the observed model parameters range with the calculated value of the model parameters and also by analyzing the misfit between the observed and calculated gravity, we concluded that the IPSO algorithm is a reliable method for estimating the sedimentary basin depth and simulating it. The IPSO algorithm has also been applied for the gravity inverse modeling of a sedimentary basin in the Northeast region of Iran.
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Regional gravity and magnetic surveys in parts of Belgaum, Bijapur, Dharwar and Raichur districts, Karnataka (India)
D.C. Naskar*, S.V.N. Chandrasekhar, Anshika Sharma, and M. Purushottam
Geological Survey of India, Southern Region, Hyderabad-500068
ABSTRACT
Regional geophysical survey, employing gravity and magnetic methods, have been carried out in 2160 sq km area of Western Dharwar Craton (WDC). The objective of the survey was to delineate subsurface structural features. The Bouguer anomaly (BA) map has brought out negative gravity anomaly with amplitude of 29 mGal in the range from -78 mGal in the eastern part to -107 mGal. The area surveyed is characterized by high gravity anomaly towards northern and east central part and low to medium gravity anomaly in the west central and southern part, except a small gravity high closure near Yankachi. The elongated residual high gravity nosing trending in nearly NW-SE direction in the central portion and flanked by residual gravity lows on either side, is inferred as basement high below Kaladgi Supergroup of sediments. Similarly, magnetic anomaly (TF) map shows bipolar magnetic anomalies in the northern and east central parts; magnitude of anomalies ranging between -81 nT to 488 nT. Presence of wide spread Kaladgi Supergroup of sediments in the central and southern part of the studied region, may have contributed for low to medium intensity magnetic anomaly except a major high south of Bagalkot in the southern part. High intensity magnetic anomaly closure around Yankachi, reflected as a zone of high analytic signal, may be attributed to Hungund schist belt towards east central part. The radially averaged power spectrum of gravity data has brought out two interfaces at depths of around 8.33 km and 3.12 km, and for magnetic data one interface at the depth of 2 km respectively. The interfaces brought out by both the gravity as well as magnetic data, may represent the range of basement depth (2-8.33 km) in the western part of Dharwar Craton. The linear clustering, trending in N-S direction of Euler depth solutions towards west central part, NE-SW trending linear cluster around Bilji-Kolhar towards central part and NW-SE trending towards northern part in Kolhar-Kakhandaki-Babaleshwar section, whereas curvilinear clustering around north of Girisagar in the central part and south of Katgeri in the southern part have been brought out. These linear and curvilinear clustering may be inferred as geologic/faulted contacts warrants for detailing the area.
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Crustal deformation rates in the Indian region from continuous GNSS measurements from 2013 to 2018 and sensitivity of plate velocity with reference frames
Sravanthi Gunti1*, J. Narendran1, Priyom Roy1, S. Muralikrishnan1, K. Vinod Kumar1, M. Subrahmanyam2 and Y. Israel2
1National Remote Sensing Centre, Indian Space Research Organization (ISRO), Balanagar, Hyderabad-500037, India
2Department of Geophysics, Andhra University, Visakhapatnam-530017, India
ABSTRACT
The Indian plate velocity for six IGS (International GNSS Service) stations was re-estimated by processing the GNSS datasets for the period January, 2013 to December, 2018 in International Terrestrial Reference Frame 2008 (ITRF2008) using long baseline GNSS scientific software Bernese 5.2. Out of these six IGS stations, two stations IISC in Bengaluru and HYDE in Hyderabad are located on the Deccan plateau, two stations LCK3 and LCK4 in Lucknow are located in the Indo-Gangetic plain and the remaining two stations, PBRI and PBR2 are located in the Port Blair area of Andaman Islands. Totally, 13 IGS sites data have been used as reference stations; 6 sites being located in the Indian plate and the remaining 7 sites in the adjacent plates (Eurasian plate, Arabian plate, and Australian plate). The result indicates that Indian plate is moving with a velocity of 54±0.6 mm/year at Hyderabad, 55±0.8 mm/year at Bengaluru, 48.5±0.95 mm/year at Lucknow and 21.5±1.2 mm/year at Port Blair. The results confirm that Southern part of India is moving as a rigid plate at velocity of 48 to 55 mm/year and the Andaman area, at a velocity of 21 to 22 mm/year in North East direction. The sensitivity of the velocity estimates with reference to the different Terrestrial Reference Frames namely ITRF2005, ITRF2014 has also been analysed.
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2D-Electrical resistivity tomography for groundwater exploration in Archean hard rock terrain in villages of Ottapidaram Taluk, Thoothukudi District,Tamil Nadu, (India)
T. Jeyavel Raja Kumar*1, P. Saravanan1, C. Dushiyanthan1, B.Thirunelakandan2 and M. Senthilkumar3
1Department of Earth Sciences, Annamalai University, Annamalai Nagar – 608002, India
2Department of Geology, Jawahar Science College, Neyveli – 607802, India
3Department Geology, Presidency College, Chennai-600005, India
ABSTRACT
Assessment of groundwater potential was done using Electrical Resistivity Tomography (ERT) in a part of hard rock terrain in Ottapidaram Taluk, Thoothukudi District of Tamil Nadu. The study area is located between 8º50´ to 9º00´ N and 78º05´to78º15´E. Geologically, the region comprises Archean gneiss, charnockite and quartzite intrusions. The ERT was carried out at four locations, Sinthalakatttai, Sillanatham, Mupplipatti and Saverimangalam. SYSCOL JUNIOR Switch-48 model resistivity meter is used and Wenner-Schlumberger configuration was adopted. Length of the profile is144 m and 48 electrodes were planted in straight line at an interspacing of 3 m. The measured resistivity data was interpreted using RES2DINV software and maximum depth interpreted was 26 m bgl. The interpreted resistivity model represented 4 layered subsurface geoelectrical structures. The overall resistivity varied from < 5 Ohm m to > 350 Ohm m. Low resistivity range was noted in Saverimangalam and high resistivity range in Sillanatham. The low resistivity observed is due to highly weathered or jointed rocks with water saturation, while the high resistivity may be related to poorly weathered rock with lack of water saturation. From the resistivity models, it is inferred that the study locations have fractured layer zones at shallow depth level up to 15m bgl at Sinthalakattai, Sillanatham and Mupplipatti locations, indicating favourable zones for groundwater occurrences. The existing bore well lithology matches with the interpreted resistivity model, indicating reliability of the ERT study for groundwater exploration.
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Interplay between climate, tectonics and sea level changes in shaping the geomorphic landscape of the Mainland Gujarat, western India: A review
Nikul P. Desai* and Shital H. Shukla
Department of Earth Science, Gujarat University, Ahmedabad, Gujarat
ABSTRACT
The landscape of Mainland Gujarat has experienced processes which are governed by external forcings viz., climate, tectonic and sea level changes. However, the studies carried out so far have been focused on each of these factors in different pockets of this vast region. The Kachchh region has mostly attracted research on tectonic aspect of Quaternary period and the Mainland Gujarat on tectonics as well as palaeoclimatic changes. In this review, we attempt to analyse all the available information pertaining to external forcings and their mechanisms, to evaluate the lacuna in the landscape evolution model and identify pathways for future research, especially in the Mainland Gujarat region. The climatic and tectonic studies have often not been integrated to deconvolute the imprints of each forcing in quantitative aspects. The review highlights the need for more chronologically supported analysis, which would be more quantified in nature rather than qualitative. The term neotectonic activity has been used widely in context of Gujarat, which needs to be supported with chronology for the realistic assessment of tectonic attributes.
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Investigations of organic matter in meteorites using Fourier transform infrared and micro-Raman spectroscopic methods: Implications for origin of extraterrestrial organic matter
Bhaskar J. Saikia1*, G. Parthasarathy2 and Rashmi R. Borah3
1 Department of Physics, Anandaram Dhekial Phookan College, Nagaon -782002, India
2School of Natural Sciences and Engineering, National Institute of Advanced Studies,Indian Institute of Science Campus, Bengaluru-560012, India
3Department of Physics, Nowgong College (Autonomous), Nagaon 782001, India
ABSTRACT
We present here the evidence for the presence of organic matters in Dergaon, Mahadevpur and Natun Balijan ordinary chondrites using Fourier transforminfrared and micro-Raman spectroscopic technique. The Fourier transforminfrared spectrum of these ordinary chondrites in the range 2700–3000 cm-1 indicates the presence of CH3 asymmetric stretching, and CH2symmetric and asymmetric stretching modes due to aliphatic hydrocarbons. The micro-Raman spectrum exhibits the diamond and graphite peaks correspondingly at 1331 cm-1, 1349 cm-1 and 1588– 1618 cm-1. The full wave at half maximum value correspondingly 120 cm-1, 70 cm-1 and 17.5 cm-1for Dergaon, Mahadevpur and Natun Balijan, indicate the nature of disordered phase involved shock metamorphism in the meteorites. The diamond and graphite peaks intensity ratios of ~1.121, ~1.075 and ~0.532, correspondingly for Dergaon, Mahadevpur and Natun Balijan, indicates the disordered nature of graphite. This study has strong implications in understanding of the origin of organic matters in extra-terrestrial materials and origin of extraterrestrial life.