Gem pegmatite is abundant in Chitral, Gilgit, Hunza and Skardu in the northern part of Pakistan. The entire northern area of Pakistan comprising the high Hindukush, Karakorum, which bears large extensive batholiths, contains pegmatite fields along the granitic margins. This region is located in one of the most geologically dynamic environments in the world that is at the suture zone along which the Indo-Pakistan and Asian crustal plates have collided. It is comprised of three major crustal elements or domains. From north to south, these are the components of the Asian Plate which are thrust over the andesitic Kohistan Island arc their boundary being marked by the Main Karakoram Thrust or MKT, the Kohistan Island Arc which has been ob-ducted onto, the elements of Asian Plate. The boundary between the latter two components is marked by the Main Mantle Thrust which is location of a past sub-duction zone and is the western continuation of the Indus-Tsangpo suture zone. The MKT and MMT are characterized by outcrops of ophiolitic and meta-volcanic rocks which record the suturing of the Kohistan arc to the Asian continent to the north and to the Indian subcontinent to the south. Through hundreds of thousands of pegmatite occur in various pegmatites fields of northern Pakistan.
Along the Karakorum Highway you can observe different geomorphologic structures and different types of rocks. There are mainly metamorphic, Meta igneous volcanic and some sedimentary rocks. The geology of Kohistan is different and unique in the area, containing mafic and calalkaline types of rocks. Kohistan constitute about 36000 sq. kilometers of the territory located between Indo-Pakistan and Eurasian plates, on the north western side of the Himalayas. This part is known as the tectonic zone of Karakoram. The area of Gilgit and Baltistan are mostly over lying by sedimentary rocks of younger age. There are large and small outcrops of intrusive acidic, intermediate and ultramafic rocks. In the eastern part near Chilas and Besham the ultramafic rocks exposed. Bulk of Kohistan sequence consists of Amphibolites, Diorites and associated volcanic rocks. Structural observations show that due to collision of two plates, Hindu Kush, Himalayas, Karakorum and other mountains were built different structures shows the sub-duction and also ob-duction of two plates. The oceanic plate is heavier than the continental plate so, oceanic plate sub-ducted under the continental plate. Geologically there are three main parts of region, Indian Plate or Indian Mass, Asian Plate or Asian Mass and Kohistan sequence.
In Swat Valley this suture is represented by talc carbonate schist, which is the host for gem quality emeralds. In Kohistan the basement is represented by deep crystal and upper mantle rock (ultramafics and garnet granulites) of Jijal complex, followed by metavolcanics of Komila amphibolites belt, and the Chilas complex (layered intrusion consisting of gabbros (Norited, Choromitites and ultramfics). Volcanic arc of Kohistan is represented by Chalt volcanic, which is overlain by marine sediments of Yasin Group.
The MKT, Main Karakorum Thrust that is the collision of the Indo-Pak and the Eurasian plate located at the Chalt-Nagar Valley. The history of tectonic evolution has very close relationship with different period of organic movement caused by under thrust of Indo-Pakistan (Indian) plate, north below the Eurasian Plate. Geologically millions of years ago, now the Northern Areas of Pakistan were submerged under a sea called “Tethyn” between Indo-Pak and Eurasian plate. During this collision Indo-Pak plate sub-ducted under the Eurasian plate, which is still going on, about 5cm per year. During this organic movement Tethyn Sea disappeared and reduced to now Arabian Sea when plates became closed. The remained material of the sea and newly erupted material by lava formed two Island arcs, Kohistan Island arc (Jajil to Chalt) and Ladhk Island arc (some parts of Baltistan is on Ladhk Island arc). Both plates have now continental parts. Due to this continental collision raise of Karakorum and Himalayas took place, which are highest as well as youngest mountain ranges in the world. Indo-Pak plate is still sub-ducting under the Eurasian plate. The mountain chain being squeezed upward as the Indo-Pak plate pushes against the Eurasian plate. The mountains are rising at an average rate of 7mm per year. Actually the mountains are raising highly due to this effect the rate of denudation is also high. In this way canyons and gorges become deeper and deeper.
ITINERARY Day-01: Arrival to Islamabad Day-02: Fly to Gilgit or drive to Chilas Day-03: Dassu Haramosh Day-04: Proceed towards Guray, visit of mines Day-05: Kutwal Lake Day-06: Visits of mines Day-07: Trek back to Dassu- drive Gilgit Day-08: Drive to Hunza Karimabad, Day-09: Visit ruby mines at Donydas and visit to Summyar in Nagar, visit to local shops Day-10: Drive to Gilgit Day-11: Fly to Islamabad or drive to Islamabad Day-12: Departure