Episodic rapid uplift in the Himalaya revealed by sup 40 Ar/ sup 39 Ar analysis of detrital K-feldspar and muscovite, Bengal fan

Journal Article · Sun Apr 01 00:00:00 EST 1990 · Geology; (USA)

OSTI ID:6357576

Harrison, T M; Copeland, P ^[1]

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1. State Univ. of New York, Albany (USA)

Detrital K-feldspar and muscovite samples from Ocean Drilling Program Leg 116 cores have been dated by the {sup 40}Ar/{sup 39}Ar technique and have depositional ages from 0 to 18 Ma. From 4 to 13 individual K-feldspars and 1 to 12 individual muscovites have been dated from 7 stratigraphic levels. In every level at least one K-feldspar and one muscovite yielded a minimum age identical, within uncertainty, to the age of deposition. These results indicate that a significant portion of the material in the Bengal fan is first-cycle detritus derived from the Himalaya. Therefore, the substantial amount of sediment deposited in the distal fan in early to middle Miocene time can be ascribed to a significant pulse of uplift and erosion in the collision zone at this time. Moreover, these data indicate that throughout the Neogene, some part of the Himalayan orogen was undergoing rapid erosion (1 to 10 mm/yr); this erosion must have been less than or equal to uplift relative to sea level. The lack of granulite facies rocks in the eastern Himalaya and Tibetan plateau suggests to us that very rapid uplift must have been distributed in brief pulses over different parts of the mountain belt. These data are incompatible with tectonic models in which the Himalaya and Tibetan plateau are uplifted either uniformly over the past 40 m.y. or mostly within the past 2 to 5 m.y.

• OSTI ID: 6357576
• Journal Information: Geology; (USA), Vol. 18:4; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CONTINENTAL MARGIN
AGE ESTIMATION
HIMALAYAS
OROGENESIS
INDIA
ARGON 39
ARGON 40
DEPOSITION
DRILL CORES
EROSION
FELDSPARS
GROUND UPLIFT
ISOTOPE DATING
ISOTOPE RATIO
MIOCENE EPOCH
MUSCOVITE
PLATE TECTONICS
SEA LEVEL
SEDIMENTS
SOURCE ROCKS
STRATIGRAPHY
ARGON ISOTOPES
ASIA
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CENOZOIC ERA
DEVELOPING COUNTRIES
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GEOLOGIC AGES
GEOLOGY
ISOTOPES
LEVELS
LIGHT NUCLEI
MICA
MINERALS
MOUNTAINS
NUCLEI
RADIOISOTOPES
SILICATE MINERALS
STABLE ISOTOPES
TECTONICS
TERTIARY PERIOD
YEARS LIVING RADIOISOTOPES
580000* - Geosciences