Northern Sedimentary Province,Central Axial Batholith,Southern Metamorphic Province

Northern Sedimentary Province: This province comprises the northern platform sediments of Gansser (1980). The province is bounded byCentralAxial Batholithin the south, Pak-Afghan border in the west and across the northern border of Pakistan in the north, (although it extends in Badakhshan of Afghanistan and also extends into China). Eastwards, it crosses the K2 and extends into Kashmir(Fig.1).
               The stratigraphy of western part of this sedimentary province is very poorly known. However, Devonian carbonates and shale are abundantly present and Gaetani and Leven(1993) have described a shallow water marine succession of Permian age (spanning from the Samarian to Midian) in the Rosh Gol and Trich Mir areas. They have also reported Upper Triassic dolomites and some Cretaceous carbonates.
                Eastwards in the central part of the Karakoram Range, the sedimentary basin deepens and according to Gactani et al. (1996), the northern Karakoram records the evolution of a crustal block, largely under marine conditions, overa time span of not less than 400 Ma.They recognized six major
tectonostratigraphic cycles,“Ordovician to Late Devonian, Late Devonian to earliest Permian, Early Permian to earliest Jurassic, Early Jurassic, Middle Jurassic to earliest Cretaceous, and Late Cretaceous. The cycles arc distinguished on the basis of accumulation and subsidence rates, major discontinuities and deformations. Further cast in the central Karakoram, as stated above, the basin deepens and continues northwards through southeast Pamir. According to Kravchenko (1979), the central Karakoram is a large anticlinorium, with Precambrian (?) crystalline rocks in its core. It is in contact with the Aghil synclinorium, which is related to the southeast Pamir.

               Axial Karakoram Batholith: It is a large body of batholith, called leucogranite by Gansser (1979), and is known as the “Kesu Koghozi, Buni Zom Pluton etc. Eastwards, many different names are applied to this batholith. Granite intrusion is typical. The Kesu-Koghozi Pluton in the Drosh/Shishi area is highly complex and has steeply foliated dioritic rocks with minor acidic intrusions. The northern margin is migmatitic granodiorite gneiss. Eastwards, the continuation of the batholith known as theGamu Bar, also named as Dobargar and Zagar-Umalsit plutons by Le Fort ct al. (1997). Granitoid rocks in further eastern part are the homblende-biotite granodiorites to granites.They have yielded K-Ar agesof 56 to 40 Ma (Casnedietal., 1978).

              Further cast in the central part, the ages of the granitoid rocks arc much older; infact, according to

Belyaevskyi (1965), the axial part of the Central Karakoram is a geanticline, which was an island arc
at least fromSilurian to LateJurassicorlater.

Southern Metamorphic Province:

Gansscr (1979) defined it as South Karakoram schists, marble and gneiss zone. Searle (1991) named it Karakoram Metamorphic Complex especially the eastern part,and Gaetani ct al.(1996) named it Southern Metamorphic Belt.

                 This province is exclusively metamorphic with some plutonic rocks. The province extends
from Drosh in the west and continues northeastwards along the southern edge of Karakoram Axial
Batholith. Stratigraphic units mapped in the western part of the province, in oneform or theother, are
largely the portions of the Darkot Group of Permo-Carboniferousage. Further northeast in theLower
Hunza Valley, lie the rocks of a prc-Himalayan (Hercynian) oceanic belt composed of carbonates,
shales and sandy formations.Towards north, these contain marble beds, which host the Hunza rubies
belong to the Baltit group. Southwards, the Northern Suture Zone delineates this province from the
Kohistan island arc.