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 04:00:00 EDT 1990 · Geology; (USA)

OSTI ID:6357576

Harrison, T M; Copeland, P ^[1]

---

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

Related Subjects

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