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

S. S. Merh ¹, N. M. Vashi ¹, J. P. Patel ¹

Affiliations
1 Department of Geology, M. S. University, Baroda, IN

Abstract

No Abstract.

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J. N. Malik ¹, Aniruddha S. Khadkikar ², S. S. Merh ²

Affiliations
1 Department of Geology, M.S. University of Baroda, Vadodara 390002, IN
2 Department of Geology, M,S. University of Baroda, Vadodara 390002, IN

Abstract

The late Quaternary continental succession exposed along the cliff-like banks (15-35 m) of the Mahi river basin comprises sediments of fluvial and aeolian origin and provides an opportunity to assess palaeoclimatic changes in western India. Seven different facies are recognized in the exposed sediment succession. The trough cross-stratified conglomerates (Gt) formed due to downstream migration of trains of sinuous-crested dunes in shallow channels, whereas the formation of planar cross-stratified gravels (Gp) is attributed to downstream accretion of the avalanching front of a mid-channel bar, The horizontally stratified sands (Sh₁ ) represent overbank deposits, while similar facies (Sh₂ ) owes its origin to infrequent sheet flooding events. The trough cross-stratified sands (St) appear to be a product of low-stage river processes. The 'loess-like' massive silts (Sim) are of aeolian origin. The calcic palaeosol facies (P) are represented by vertisols at the base and brown soils and calcic red soils towards the top indicating changing palaeoenvironments.

The overall sediment succession was built through three major climate-controlled aggradation phases. Aggradation phase 1, which is represented by gravel-bed rivers and coexistent vertic palaeosols, indicates a significantly wetter climate. Aggradation phase 2 points to a comparatively drier period during which suspended-load rivers existed. Within this phase, red soil formation suggests a climatic amelioration event around 40 ka B.P. to 23 ka B.P. Aggradation phase 3 reflects a period of extreme aridity and is manifested as the capping aeolian facies. This phase is thought to be in tandem with the Last Glacial Stage event. Stabilization of these dunes may have taken place around 6 ka B.P. as suggested by the Thar Desert palynological and lake records.

The modern Mahi channel flows due ssw. However, the palaeocurrent trends of the exposed sediment bodies reveal that the ancient drainage network in the northern sections (upper reaches) flowed due SW-SSW and in the southern sections (lower reaches) SSE, SSW and W. The present day course of Mahi is relatively younger and follows structural lineaments that developed during the Holocene (after 6 ka B.P.). The aIluvial sedimentation record is unrelated to the modern Mahi river, but is a product of ancient late Quaternary rivers which now stand either fully or partially destroyed.

Keywords

Quaternary, Palaeoclimate, Deserts, Palaeosol, Calcrete, Gujarat.

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M. G. Hardas ¹, S. S. Merh ¹

Affiliations
1 Department of Geology, M. S. University of Baroda, Baroda, IN

Abstract

No Abstract.

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O. K. Shah ¹, S. S. Merh ¹

Affiliations
1 M. S. University of Baroda, Baroda 390002, IN

Abstract

An early NW-SE trending anticlinal structure in quartzites is distorted by the super-imposition of late E-W flexures, perhaps generated during late Krol Thrust movement. The N-S to NNE-SSW flexures and N-S transverse faults comprise the last deformational event. The occurrence of any thrust at Ramgarh is ruled out as it is found that the so called 'porphyries' of Ramgarh extend Southward uninterruptedly up to Ranibaug, These porphyries are keratophyric and genetically related to the spilites of Bhimtal-Bhowali area. The supposed Nagthat quartzite-slate sequence above spilites is more likely to be equivalent to Blaini. This sequence together with spilite and keratophyric rocks comprises the lower portion of the Krol Group. The spilites represent the geo-synclinal volcanism in a shallow basin, which was followed by the deposition of Blaini, Infra-Krol and Krol.

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S. J. Desai ¹, M. P. Patel ¹, S. S. Merh ¹

Affiliations
1 Geology Department, M. S. University, Baroda-390002, IN

Abstract

The crystalline rocks of Balaram-Abu Road area comprise a varied assemblage of metamorphic and igneous rocks of Precambrian age. Earlier workers have considered the rocks of the area to belong to the Alwar & Ajabgarh Series of Delhi System intruded by mafic rocks and granites. These rocks are petrologically more complex and ate much older-Aravallis or even earlier. The mineralogical assemblages of these rocks suggest metamorphism under pyroxene granulite facies, pointing to anhydrous or dry conditions.

These granulitic rocks are seen involved in Delhi deformation and later invaded by the Erinpura granite. A superimposition of contact metamorphism (due to Erinpura granite) on the granulites, has caused the development of hornfelsic rocks containing andalusite. The rocks of Balaram-Abu Road area thus comprise a polymetamorphic terrain.

The abundance of cordierite and its association with garnet and hypersthene in pelitic granulites, the occurrence of scapolite and diopside in calc-granulites, the coexistence of olivine and plagioclase in basic rocks, absence of garnet in charnockitic rocks and the development of horn felsic rocks with andalusite indicate that the rocks of the area belong to a low pressure granulite province of metamorphism.

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S. V. Deshpande ¹, S. S. Merh ²

Affiliations
1 Institute of Petroleum Exploration, Oil and Natural Gas Commission, Kaulagarh Road, Dehra Dun 248 195, IN
2 Geology Department, M. S. University of Baroda, Baroda 390002, IN

Abstract

Wagad Hills in the eastern part of Kutch, Western India, mainly comprise of rocks ranging in age from middle Jurassic to lower Cretaceous encircled by a thin and narrow fringe of Tertiary sediments.

A sedimentary model of Wagad Hills is proposed comprising environments of deposition, basin geometry, lithic fill, lithic arrangement, directional structures and tectonic setting. The area experienced a prograding delta system with a gradual shift of strand line from east to west during the course of deposition.

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Geeta Desai ¹, M. G. Hardas ², M. P. Patel ¹, S. S. Merh ¹

Affiliations
1 Department of Geology, M. S. University of Baroda, Baroda 390002, IN
2 Regional Laboratories, Oil & Natural Gas Commission, Baroda 390009, IN

Abstract

Miliolites occur within the Kutch highlands as thin horizontal sheets occupying topographic depressions or as obstacle dunes resting against the slopes of big hills. Sheet deposits of the low-lying ground, reveal a marine origin and are seen to consist of pellets and microfossils embedded in a micritic to fine sparry matrix. These valley-fill sheet deposits are characterised by a faunal assemblage typical of warm, clear, shallow, carbonate-rich sea, where terrigenous influx was poor. On the other hand, the obstacle dunes typically comprise aeolinites and appear to have developed during the regression of the sea, the strong winds having lifted the exposed carbonate sands and dumped them against the nearby hillsides. The higher strand line indicated by these marine miliolites could be related to one of the Quaternary transgressions.

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S. S. Merh ¹

Affiliations
1 M. S. University of Baroda, Baroda, IN

Abstract

No Abstract.

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S. Ganapathi ¹, S. S. Merh ¹

Affiliations
1 Dept. of Geology, M. S. University of Baroda, Baroda 390002, IN

Abstract

The various geomorphic features point to a sequence of transgression (+20 m), regression (-10 m), transgression (+6 to +8 m) and regression (present-day sea-level) which acted over a coastline, which also showed differential movement along the Shetrunji Fault.

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S. S. Merh ¹

Affiliations
1 Department of Geology, M. S. University of Baroda, Baroda 390002, IN

Abstract

The constituent rocks of Neogene are conglomerates, grits, silty sandstones, marls and argillaceous limestones. Marine Quaternaries are represented by the miliolite rocks of Saurashtra (Middle Pleistocene) and younger Holocene Rann sediments, mudflats and beach rocks. The transition of Neogene to Quaternary is not fully understood. Perhaps regressive conditions prevailed during the close of Pliocene and in the early Pleistocene. Evidences point to a bw strandline during the Lower Pleistocene. The Quaternary period is marked by two major transgressions-one in Ihe Middle Pleistocene and the other at the advent of Holocene. The Middle Pleistocene transgression gave rise to the miliolites, whereas the Holocene marine deposits are related to the last post glacial transgression.

The Neogene-Quaternary sequence requires further examination, particularly the so-called Pliocene, Plio-Pleistocene and Lower Pleistocene rocks. As the N-Q sea levels were related to climatic changes, a close scrutiny of the onshore continental record just above the marine Neogene rocks might provide some information towards fixing the nature of transition of Neogene to Quaternary. It would be essential to apply alternative criteria such as palaecmagnetic and therrnoluminiscence measurements and radicmetric age determinations for obtaining a clearer picture.

Keywords

Neogene-Quaternary, Gujarat.

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V. Sridhar ¹, S. S. Merh ¹

Affiliations
1 Department of Geology, M.S.University of Baroda, Baroda-390002, IN

Abstract

A thickness of over 300 m of dominantly alluvial sediments in the north Gujarat plains suggest that the sedimentation took place during the late Quaternary period in a huge graben bounded by faults that are related to the Cambay basin. An ancient super fluvial system was responsible for this vast accumulation. Most of the present day rivers are the remnants of that former system and have exposed the sediments in cliff sections. The present course of the Sabarmati appears to be unrelated to the former system for much of its length. Its course is controlled by a major lineament that developed subsequent to the deposition of the entire sequence. The earlier course of the river is now represented by the river Rupen. The uplift of the Aravallis during the Mid-Late Quaternary and the eustatic sea level changes might have disrupted the older system.

Keywords

Geomorphology, Quaternary, Sedimentation, Cambay Basin, Gujarat.

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A. S. Khadkikar ¹, L. S. Chamyal ¹, J. N. Malik ¹, D. M. Maurya ¹, S. S. Merh ¹

Affiliations
1 Department of Geology, M.S. University of Baroda, Vadodara - 390 002, IN

Abstract

A more or less complete conformable succession of sediments of Quaternary age is documented from the Mahl river basin. A description of the lithostratigraphy is accompanied by the palaeoclimatic inferences drawn on the basis of deduced depositional environments, which shows a remarkable broad correspondance with global climatic fluctuations.

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V. Sridhar ¹, S. S. Merh ¹, L. S. Chamyal ¹

Affiliations
1 Department of Geology, M.S. University of Baroda, Baroda-390 002, IN

Abstract

The area bound by the rivers Sabarmati and Luni forming a part of North Gujarat and Southwest Rajasthan alluvial plains has preserved in its sediments and landscape various changes which have occurred in the drainage systems during the Upper Quaternary times. The present day drainage mainly cuts across the material deposited by a set of older rivers which now stand disrupted. The present day rivers are observed to have been superimposed over older river channels and dominantly follow numerous tectonic lineaments and faults of a later date. The new channels reveal and have preserved relicts of the earlier fluvial system. Geomorphic and drainage studies reveal existence of two ancient major river systems, the remnants of which are now represented by the Banas and Rupen rivers. The Banas, along with its major tributary Sipu is the sole survivor of the older fluvial system. whereas Rupen has been partially destroyed.

Keywords

Geomorphology, Drainage Systems, Quaternary, North Gujarat.

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Parasg S. Sohoni ¹, Javed N. Malik ¹, S. S. Merh ¹, R. V. Karanth ¹

Affiliations
1 Department of Geology, M. S. University of Baroda, Vadodara - 390 002, IN

Abstract

Katrol hills occupy the central Kachchh mainland and belong to an area of active tectonism. This area is one of the few seismically and tectonically active areas outside the Himalayan mountain belt. A longitudinal fault flanks the hills to the north (Katrol Hill Fault Scarp) and morphotectonic analysis along this hill range has confirmed that the area has undergone differential tectonic uplift. Various geomorphological criteria viz., mountain front sinuosity, faceting, facet dissection percentage of 62 fronts of two sub-areas, valley floor to valIey height ratios and concavity indices of the streams flowing due north and south of Katrol hills reflect the amount of influence of tectonic activity during Quaternary times. Pattern of seismicity in the area reveals that all the known earthquakes in this region fall more or less in the Katrol Hill Zone running E-W for about 100 km. The warping of Quaternary rocks further furnishes field evidence of tectonic activity in post Upper Pleistocene times. Morphometric analysis along with seismic pattern and geological evidences indicate that the Katrol Hill Zone continues to be tectonically active.

Keywords

Neotectonics, Geomorphology, Katrol Hills, Kachchh, Gujarat.

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Javed N. Malik ¹, Parag S. Sohoni ¹, R. V. Karanth ¹, S. S. Merh ¹

Affiliations
1 Department of Geology, M. S. University of Baroda, Vadodara - 390 002, IN

Abstract

No Abstract.

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S. S. Merh ¹

Affiliations
1 5, Ashdown Court, 5 ldmiston Rd, Worcester PK Surrey, KT47SE, GB

Abstract

No Abstract.

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S. S. Merh ¹

Affiliations
1 25/311, Punitnagar, New Sama Road, Vadodara - 390 008, IN

Abstract

The Great Rann of Kachchh comprises aunique geomorphrc entity of the Indian sub-continent It is a mystenous and fascinating tectonic landscape generated during last 10,000 years, In an area marked by sea-level changes Tectonically, the region of Kachchh is located quite close to the junction of the Western Continental Margin and the geosynclinal belt of Sindh-Baluchistan Its proximity to the triple junction formed by the Indian, Arabian and African plates has further complicated its tectonics The region is frequently visited by earthquakes, whose focal mechanisms indicate reverse faulting generated in a compressional stress field Geomorphically, the Great Rann can bc divided in to four units, based mainly on the topographic characteristics and annual inundation pattern Kachchh in general and the Great Rann In particular have been vlslted by earthquakes all throughout then geological history Two major seismic events of the ncar historical past are the 1819 Allah Bund Earthquake along the northern margin of the Great Rann, and the 2001 Bhuj Earthquake that was located on the southern margin Apart from its geomorphic and seismic uniqueness, the Great Rann has considerable geoarchaeological significance A few thousand years back, perhaps even prior to the times of Rig Veda, several Himalayan rivers viz, Sindhu (Indus), Shatadru (Proto-Sutluj) and Sarasvati,f lowing across the northwestern plains of India, emptied their waters into a shallow sea that now marks the site of the Great Rann Navigating along these rivers, mainly Sarasvati, the Indus Valley people came to Gujarat and established several important Harappan towns

This paper provides an insight into the close relationship that existed between the geomorphology, seismicity and archaeology of the Great Rann.

Keywords

Geomorphology, Seismicity, Geoarchaeology, Great Rann of Kachchh, Gujarat.

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