Wyniki wyszukiwania - BazTech

Ograniczanie wyników

1 Studia Geomorphologica Carpatho-Balcanica

1 2015

Powiadomienia systemowe

Sesja wygasła!

Znaleziono wyników: 1

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: maturity of soils

Sortuj według:

Ogranicz wyniki do:

Reconstruction of Late Quaternary neotectonic movements and fluvial activity in Sikkimese-Bhutanese Himalayan Piedmont

Starkel L., Płaskonka D., Adamiec G.

Studia Geomorphologica Carpatho-Balcanica

2015

Vol. 49

71--82

In the part of Sikkimese-Bhutanese Himalaya the youngest Siwalik overthrust had not developed, and the piedmont zone with extensive fans forms a semicircular gulf dismembered by several faults and minor overthrusts. Some uplifted parts of older deformed alluvial fans contain the lenses of organic clays which were earlier dated at 22–34 ka BP by 14C method. Various elevated levels differ also in soil maturity. It means that the main tectonic activity with overthrusting could occur later. To distinguish various alluvial formations and phases of tectonic activity the authors dated older levels in several localities by OSL method as well as investigated soil profiles. Most mature soils over elevated blocks built of coarse alluvia were dated between 50 and 60 ka BP. Probably the previous 14C dates from clays are too young, and on the contrary OSL dates are overestimated. The younger generation of fans (10–15 m high) dated at about 14 ka coincide with the start of monsoonal pre-Holocene activity. The authors try to correlate these phases with terraces and tectonic activity in the most eastern part of the Himalayas (two phases of overthrusting: after 50 ka and 10–5 ka BP) as well as with events outside the piedmont zone: glacifluvial aggradation in the Tista valley during advance of glaciers in Sikkim and with sequence of deposits in the Brahmaputra delta.