Informatics Publishing Limited

T. N. Bagati ¹

Affiliations
1 Wadia Institute of Himalayan Geology, Dehra Dun, IN

Abstract

Three major microfacies viz., micrite, sandy micrite and sparite recognised recur at various stratigraphic levels. Illite and chlorite are the only clay minerals present. By analogy with recent carbonates, the carbonate microfacies of the Kakarhatti limestone indicates deposition in shallow marine conditions, oscillating between supratidal and intertidal. The main diagenetic features observed are reduction in porosity, silicification, pressure solution and recrystallization.

Full Text

     

R. Kumar ¹, T. N. Bagati ¹, R. K. Mazari ¹

Affiliations
1 Wadia Institute of Himalayan Geology, Dehradun-248001, IN

Abstract

Sediment build up, structure and geomorphic setting of alluvial fans can serve as good clues for the reconstruction of Quaternary events in a region where they are located. Alluvial fans assume greater importance especially in young orogenic belts like the Himalaya where there has been an interplay of rapid uplift and global climatic change during the Pleistocene. In this paper an attempt has been made to study the genesis of a small relict debris fan in the upper Spiti valley in the Tet hys Himalaya (H.P.) and to elucidate its sedimentational style in local climatic and tectonic set up. The fan has been essentially constructed by debris flows and subordinate stream deposits during seasonal melting and episodic events of the late Quaternary. While climate remained much the same local tectonic activity leading to upliftment of the fan and diversion of the feeder channel ceased further accretion of the fan beyond its present size. Minor warmer climatic oscillations within the main cool phase are observed.

Keywords

Spiti Valley, Geomorphology, Himachal Pradesh.

Full Text

     

Anil K. Mundepi ¹, T. N. Bagati ¹

Affiliations
1 Wadia Institute of Himalayan Geology, 33, General Mahadeo Singh Road, Dehradun-248001, IN

Abstract

The physico-chemical and X-ray diffraction analysis of the oolitic ironstone belonging to the lower part of the Subalhu Formation (Eocene) reveal the presence of major berthierine and chamosite with minor amounts of hematite, limonite and rarely glauconite. Quartz. polycrystalline quartz, siderite and chert are important accessories .

The ironstone ooids having the alternate coalS of berthierine/chamosite and ferric oxide were formed under changing physico-chemical conditions. Mineralized solutions containing iron and silicates replaced the carbonate ooids and other detritus during diagenesis. The ooids were fractured and distorted due to intergranular solution readjustment during compaction and later tectonics.

Keywords

Ironstone Ooids, X-Ray Diffraction, Diagenesis, Himalaya.

Full Text

     

N. Suresh ¹, T. N. Bagati ¹

Affiliations
1 Sedimentology Group, Wadia Institute of Himalayan Geology, 33, General Mahadev Singh Road, Dehra Dun-248 001, IN

Abstract

Sedimentology, mineralogy and geochemistry of ooid sand beds in deep sea gravity cores (water depth >2818 m) reveal that they were derived from continental shelf by turbidity currents. The presence of ooid turbidites at two different levels suggests two periods of turbidity current activity. The first activity probably took place during the Last Glacial Maximum in Late Pleistocene and the second activity prior to the stabilization of sea level in the Early Holocene.

Keywords

Sedimentology, Turbidites, Late Quaternary, Bengal Fan.

Full Text