The oldest sedimentary and metasedimentary rocks exposed
in the Himalayan foothills of Pakistan record a gradual transition
seaward from the evaporites of the Salt Range Formation to pelitic
sediments deposited in deeper water to the north. The Upper
Proterozoic Tanawal Formation was derived from erosion of a
northern highland produced during the early stages of Late
Proterozoic to early Ordovician tectonism. Early Paleozoic tectonism
is indicated by an angular unconformity at the base of the Paleozoic
section, the intrusion of the Mansehra Granite, and the local
removal of Cambrian strata. Paleozoic shallow-marine strata are
preserved in half-grabens created during extensional tectonism
that began during the Carboniferous and climaxed with rifting
during the Permian. Paleozoic rocks were largely or completely
eroded from northwest-trending highlands on the landward side of
the rift shoulder. Thermal subsidence of the rifted margin resulted
in transgression of the highlands and deposition of a Mesozoic
section dominated by carbonates. Compressional tectonism related
to the impending collision with Asia commenced in the Late
Cretaceous. Rocks north of the Panjal-Khairabad fault were
deformed and metamorphosed during Eocene subduction of
northern India beneath the Kohistan arc terrane. Following their
uplift and exhumation, rocks metamorphosed beneath Kohistan
were thrust southward over unmetamorphosed rocks along the
Panjal and Khairabad faults which are inferred to be connected
beneath alluvium of the Haripur basin. Contrasts in stratigraphy
and metamorphism on either side of the Panjal-Khairabad fault
indicate that shortening on this structure exceeds that of any other
fault in the foothills region. The migration of deformation towards
the foreland produced south- or southeast-vergent folds and thrust
faults in strata south of the Panjal-Khairabad fault and reactivated
Late Cretaceous structures such as the Hissartang fault. The
Hissartang fault is the westward continuation of the Nathia Gali
fault, a major structure that thrusts Proterozoic rocks in the axis of
a Late Paleozoic rift highland southward over Mesozoic strata.
Fundamental differences in stratigraphy, metamorphism, and
relative displacement preclude straightforward correlation of faults
and tectonic subdivisions of the central Himalaya of India and
Nepal with the northwestern Himalaya of Pakistan. / Graduation date: 1994
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/35578 |
| Date | 03 December 1993 |
| Creators | Pogue, Kevin R. |
| Contributors | Yeats, Robert S. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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