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

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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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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J. N. Malik ¹, A. K. Sahoo ¹, A. A. Shah ¹, A. Rawat ¹, A. Chaturvedi ¹

Affiliations
1 Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur - 208 016, IN

Abstract

We report in this note the farthest recorded liquefaction phenomenon near Jammu as sequel to the Mw 7.6,8 October, 2005 Muzaffarabad earthquake of Kashmir. The most common liquefaction features were sand blows and longitudinal en echelon fissures. Based on the occurrence of liquefaction and minor damage to the pakka houses it is suggested that the intensity would have been around VI-VII on MSK scale in this region.

Keywords

Liquefaction, Sand Blows, Muzaffarabad Earthquake, Jammu Area, Jammu and Kashmir.

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