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Chapter 05
Geological Studies
The core of the huge Rakshas anticlinorium is formed by yellowish and greenish, more or less calcareous and chloritic, sericiteschists, surprisingly recalling the Cambrian Garbyang formation. They form the lowest outcrops of the Rakshas anticlinorium, which seems to plunge slightly in a western direction and extends eastwards towards the Manasarovar Lake. Its eastern continuation is unknown, except that it may rise and be connected to a northwards spur of the large crystalline dome of the 7700 m high Gurla Mandhata.
SW
NE
ISSN 21
2
of 4150m Sutlej -
Fig.94: The Sutlej river cutting though the Rakshas anticlinorium. S Tibet; after A. GANSSER (1939) 1. Upper Chilamkurkur series calcareous) 3. Sandy calcareous schists 2. Lower Chilamkurkur series (argillaceous) 4. Black slates
Crystalline dome of the Gurla Mandhata Southeast of the famous lakes Rakshas and Manasarovar the wide Tibetan rolling hills are dominated by a huge dome-like uplift-the 7700 m high Gurla Mandhata. The morphological aspects suggest a very young uplift. The well preserved domal form and the sharply eroded deep gorges as well as its excessive height support this suggestion (Fig. 95 and Ph. 25).
Gurla Mandhata
7700
Nakonkar
-
Tibet
Nepal
Khoiarnath
Tokicko
Jitkot
Fig. 95: The gneiss dome of Gurla Mandhata. S Tibet; after A. GANSSER. Core of gneisses, covered by schists transgressed by titled traces of the Taklakot region, uppermost Karnali valley. The outer layers are formed by epimetamorphic phyllites, while the inner core exposes muscovite-biotite gneisses, not unlike the Darjeeling - type gneiss (Helm and Gansser, 1939). Sven Hedin collected crystalline rock from the northern slopes of Gurla Mandhata described by Hennig (1915). He mentions banded to lenticular two mica alkali-feldspar gneisses. The western border of Gurla Mandhata is bordered by the young gravel terraces of Taklakot in the
(193
Central Himalayan Geological Observations
