Preliminary Geology And Petrography Of Swat Kohistan

Age and Correlation : The complex, covering many thoi~snnrl Square miles,
from Afghanistan to southern Cilgi t Anency. It has been coilsidered,
lvith reservatioas, to be oldnr tho11 the Siluro-Dcvo~~~ rocks of the
Lower Swat - Buner Schistose Group by Martin ct ol. (1%2) nnd ihvias (1964).
Bskr alld Jac~rson (1964) have shown theso rocks to be Preet~mbrinn in age. It
were the quartz diorites of the complex, apparently, that Mat8sushitl.z (1965, ;
+
p. 84) called gmnite, snd correlated with tho granites of Shungi Go1 (Middle to
Barly Mesozoic) of Cilgit Agency. Jan (1070, p. 30) ~loted that tho llorites
*xtend, at least, up lo ten miles lo t'he east of Chilns and can he correlated
~17ith t8hose of the Naaga Parbnt massir. Tlie latter are gerleticnlly rclnted to
the Creto-Eocene volcanic rocks of IiasEiin ir usc2 may, thus, Lo contc; mporczneous
with, or slightly younger, than the volca~iics (Miseh, 1949, TI. 216). On these '
grounds, Jam (1970) considered the norites to havo been et~~plncecl during the :
earliest phases of the I3irnnlayan orogeny and Middle to Lt1t.o Cretacc-ous ill age,
A pegmatite hornblende near Balirtiin has been dulecl to he 67 PI. y. by IC/Ar
mcthod (Jan and Kempe, in preparation). Since the pgmcrtit ecr nre consiclered
by them to be the final products of the igneous and metamorpltic qhode which
produced the basic series of Upper Swat, EL Late Cret:mous ago can bc assigned 1
to the complex.
The Utwr Volcanics.
Grey, green, red and, rarely, white volcaaic rooks cover n large area to the
northwest of Kalam. To the oast they extend in Ushu Vnlley and to the west
in Dir. The Utror village is surrounded on all fiidcs by volcanic exposures.
Mottling of various colours, particularly the red and green, is conspicuous in
many places. In these, larger volcanoclslrsts lie in s matrix aft^ different colour.
In the red and green ones, the matrix is nearly always of green colour. This
may suggest a, higher frequency of the reddish matarial in tliu early atagos of the
volcanic activity. The green mass appeare to be more readily altered than the
red; the colour of the formor is mainly due to secondary chl.orito and epjdote,
and that of the latter due to oxidized iron ore granules.
In general, volcanoclastic rocks are more abundant than. flows. They may
be fine-grained, homogen~ons tufls or, as is often the cam, eorn~oscd of larger
fragments set in a tuffaceous or lava matrix (Pig. 2). Some aro a confused mixture
of pyroclaetios arid lava; the former &ay be over 50% in the form of frngmente
coarser than ash. The fragments may be angular or rounded, and up to a foot