Abstract:
"The thesis incorporates results on the stratigraphy,structure \nd sedi
mentation in an approximately 900 sq.km. of the Lesser Himalayan terrain along
BhagiratM river,districts Utt-rkashi and Tehri.U.P. On the basis of geological
napping on 2a=l km. scale, various lithostratigraohical units have been
established and described with their fie Id,megascopic and microscopic chara
cters. The folds, faults and thrusts have been described with their field
evidences. The structure of the area deals with their mutual interrelationshin
and is elucidated with a number of vertical cross sections. The effects
of folding and thrusting of rocks are structurally analysed in a part of the
northern region with ir -diagrams. Atectonic setup of the area has been attem
pted and is compared with adjoining regions of the Lesser Himalaya between
Simla and Kuraaon,
A number of thrusts are conspicuous by occurrences of mylonites and
metabasics which have been'dealt with respect to their field,megascooic and
microscopic characters. The metamorphism,mode of emplacement *md relationship
of mylonites and metabasics with thrusting is discussed.
The sedimentological studies include insoluble residue and chemical ana
lysis of carbonate rocks and heavy mineral investigati ns in arenaceous rocks.
The insoluble residues from dolomites and limestones are described. The chemi
cal data for calcium and magnesium is used in classification of the carbonate
rocks. The insoluble residue and CaO/MgO relationship is compared with carbo
nate formations of the Lesser Himalaya.
The heavy mineral separations from quartzites are quantitatively,quali
tatively and statistically analysed. The lateral and stratigraphies 1 varia
bility of zircon and tourmaline varieties from Quartzite Formation of the
Garhwal Group is regionally studied to show their importance in stratigraphy,
(ill)
structure ^nd tectonic interpretation. The grain size data of zircon,tourmaline
and quartz from heavy mineral separations of quartzites and thin sections of
non-calcareous sedimentary rocks is statistically represented by the Smithson
and Haggerraann diagrams for purpose of their application in correlation and
sedimentation of rocks.
The stratigraphy of the area is separately described and correlated with
other Lesser Himalayan formations. On the basis of the above studies, sedimen
tation and tectonic history of the area is reconstructed.
In the last chapter,the conclusions are briefly enumerated."
