Uplift and cooling history of the NW Himalaya, northern Pakistan - evidence from fission-track and /sup 40/Ar//sup 39/Ar cooling ages

Thesis/Dissertation · Sat Jan 01 04:00:00 EST 1983

OSTI ID:5852267

Zeitler, P K

This study reports 145 fission-track and 21 /sup 40/Ar//sup 39/Ar cooling ages from the Himalaya of northern Pakistan. Studies of the Himalaya are important because they provide geologists with an opportunity to test models of orogenesis in an active tectonic setting. As the Himalaya become better known and models become more quantitative, information about thermal histories and rates of uplift and erosion will be needed. The cooling ages suggest, and thermal modelling confirms, that throughout the Tertiary, the cooling history of northern Pakistan was controlled by the effects of accelerating uplift and erosion. On average, from 30 Ma to the present, uplift rates increased from less than 0.1 mm/yr to 0.4 mm/yr. This uplift and erosion, however, has been variable in space as well as time. The association of the Nanga Parbat-Haramosh Massif and Hunza with very young cooling ages and with rapid uplift maintained for a period of several million years is the most striking discovery made by this study. The location of these two areas at the heart of the Pamir-Himalaya Arc suggests that their anomalous behavior is linked in some way to a locally vigorous collision of India and Eurasia, possibly due to a promontory of Indian crust. Several of the cooling ages reported help constrain the emplacement ages of intrusives located in northern Pakistan. In addition, cooling ages from the southern Swat-Hazara region can be interpreted to give the time of final southward thrusting of the Kohistan Arc along the Main Mantle Thrust, at about 30 Ma.

• OSTI ID: 5852267
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580100* -- Geology & Hydrology-- (-1989)
AGE ESTIMATION
ARGON 39
ARGON 40
ARGON ISOTOPES
ASIA
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
DEVELOPING COUNTRIES
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FISSION TRACKS
HIMALAYAS
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
MOUNTAINS
NUCLEI
OROGENESIS
PAKISTAN
PARTICLE TRACKS
RADIOISOTOPES
STABLE ISOTOPES
TECTONICS
YEARS LIVING RADIOISOTOPES