Preliminary Geology And Petrography Of Swat Kohistan

of the rocks have antiperthitic plagioclase.
cloudy; and rnyrmelritic at places.
The plagioclnse may be locally
Age and Correlation : Both of the granites intrude the Deshai Diorites.
Th,a ,Matiltan Granite is also intrusive into the volcania rocks, however, the
latter are nowhere in contact with the granite8 of Dew~~ngar. Deshai diorites,
as said previously, are prabably younger than the volcanic rocks and are
considered by us to be Early Tertiary. Therefore, &Middle Terth-3;' age is
assigned to the granitic rocks. General lack of foliation in Dewangar Granite
may suggest a younger age for them than for the Matiltan Granite which, at
places, is fbliated. We are not aware of any granites in Swat, Dir, and Indus
Valley which can be correlated with those of Dewangar.
Quateifiasy Deposits.
. .
Unconsolidated deposits of glacial and alluvial origin occur along the main
valleys throughout the area.. The olluvisl deposits are generally thin and
limited in occurrence although some of the fans in Gabral and Ushu valleys are
fsirly large. Glacial deposits are especially abundant to tho north of Manlcial
in the major valleys. We have not concentrated on their study and the renders
are referred to the excellent work of Porter (1970), and that of Matsushita
(1065).
, - STRUCTURAL GEOLOGY
The Swat Kohistan, probably, comprises the nort11~~ester.n extension of the
Rimalayan lvountai~ls and the area is structurally very complex. Shear zones,
minor fanlts and folds are common throughout. Folding is better exhibited by
the Kalam Group. The contact of the volcanic rocks with the ICalam Group is ,
very complex; small blocks and beds of quartzites, rarely phyllite, occur in the
volcanic roclrs and appear to be structurally emplaced. The latttr also show
changes in dip and are folded. The general trend of the Iialnrn Group is nortlleast
- southwest, with northwesterly dip. LocaJly, there are changes in
strike and dip, especially in the phyllites to the south~&t~ of Kslrtm. At a few
places, the quartzites have been domed up seemingly by granites, near Matiltan.
The contact of the quartzites and the overlying phgllites seems to be normal,
however, IkIetsushita (1965, p. 41) has suggested a northeast - solrthwest fault
between the two in the Ushu-Kalam area.
The contact between the rocks of the Basic Complex and Ihlem Group
apljears to be intrusive although it may be locally faulted. Presence of
p0rphgrit.i~ dykes in the latter, xenoliths of quartzite in the former, and