Geological Field Report of Gilgit Baltistan

Asim.mujtaba007@geologist.com
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Geological Field Trip to Gilgit

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Submitted by: Muhammad Asim Mujtaba
313
Submitted To: Sir Imran Ahmad And Sir Asad Muhammad

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Contents
Acknowledgment…………………………………04
Abstract……………………………………………….05
Introduction…………………………………………06
General Geology…………………….…………….06
Literature review …………………………………07
Day I……………………………………………………..08
Day II…………………………………………………….16
Day III……………………………………………………24
Day IV……………………………………………………33
Outcome……………………………………………….36
References…………………………………………….36

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ACKNOWLEDGEMENT
I would like to thank Almighty Allah for giving me the
sense and strength to be a part of this field trip which
was organized by the Department of Geology
University of Malakand. In performing this field, I had
to take the help and guideline of some respected
persons, who deserve my greatest gratitude. The
completion of this field gives us much Pleasure. I
would like to show my gratitude to Honorable Sir
Imran Ahmad and Sir Asad Muhammad for giving us a
good guideline & a lot of knowledge Before & after
the field. I would also like to expand my deepest
gratitude to all those who have directly and indirectly
guided me in writing this field report.

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Abstract
Gilgit-Baltistan covering the most area of Northern Pakistan. The northern area of Pakistan
mainly compromises of three tectonic plates. These plates are Karakorum Plate, Kohistan Island Arc
and Indo-Pakistan Plate. Kohistan Island Arc is sandwiched between Karakorum plate and Indo-
Pakistan Plate by having two main trusts the MKT in the north and main mantle thrust MMT in the
south.
We observed many tectonic features such as MMT and MKT, Kohistan island arc, syntaxes,
and collision zone of Indian and Eurasian plates.
MMT lies in between Indian plate and Kohistan island arc and the MKT lies in between the
Kohistan island arc and the Eurasian plate.
We studied the petrology of different metamorphic, Meta sedimentary and igneous rocks
which were formed before, during and after Himalayan orogeny. We also studied its mineralogy
briefly.
In northern areas of Pakistan there are different type of rock complexes of igneous bodies,
different grades of metamorphic rocks, and different meta sediments groups.
The complexes, formations, the groups and the different boundaries which we studied in this field
are given below:
✓ Banded Kamila Amphibolite
✓ Chamtali Blue schist
✓ Shangla top Dunite and Serpentine
✓ Marguzar Formation
✓ Belay baba Gneisses
✓ Besham Quartzite and leucogranite
✓ Dubair Grano Diorite
✓ Jijal Complex
✓ Chillas Gabbro Norite
✓ Kohistan Batholiths
✓ Nagar Basalt and Talc schist
✓ Huza Marble
✓ Passu Slates
✓ MMT and MKT

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Introduction
The geological field was arranged by department of geology University of Malaknd for 6th
semester
students. The field was conducted on May 7th
,2018 to the northern Pakistan (Giligit, Hunza).
Day I
On day I we started our field and leave the university sharply on 6:30 am. On day I we study different
types of rocks like Kamila Amphibolite, blue schist, pyrite, Dunite, Serpentine and Augen Gneisses.
We stayed in Besham and early morning start our field again.
Day II
On 2nd
day we started our field and study the rocks of Besham which include Besham Quartzite and
Besham leucogranite. Then after that we study Dubair Grano Diorite, Jijal Complex, Pathan
Amphibolite. The Jijal complex includes Dunite, Serpentine, pyroxenite, hornblendite, pyroxene
Granulite. We also study the MMT.
Day III
On day 3rd
we started our field and study different rocks of Chillas area including Gabbro Norite,
Mylonites and Gneisses. Further on this day we study Kohistan Batholiths and Chalt volcanos. After
that we study the rocks of Nagar Distract which includes Pillow Basalt and Talc Schist. Here we also
study the MKT.
Day IV
On day 4th
we study two types of rocks, the first one is Hunza Marble, which is very economical and
famous all over the world because of having Ruby. After that we study the Passsu Slates.
General geology:
The tectonic setting of that area is highly complex and the rocks are also highly deformed.
We studied rocks of two different plates during this tour Indian, Eurasian and Karakorum block
(minor plate) mountain series seen. The suture zone MMT in Kohistan separates K.I.A form Indian
shield rocks. Different metamorphosed rocks are observed which are formed due to collision
between Indian and Eurasian plate about 50 mya. And some are due to igneous intrusions. The age
of K.I.A is about 90 to 110 mya. MKT thrust point lies between Eurasian plate and K.I.A. we study
different rocks of Gilgit, Chillas and Hunza. The rocks include Amphibolite, Dunite, Serpentine,
Hornblendite, Pyroxenite and many more.
Finally, our main objects of total field are to observe different type of rocks and study it with
lenses to identify their essential and accessory mineral for the identification the rock types, minerals
texture, grain shape and to observe different structures (fault, folds, joint) in the field work area.

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Literature review:
R.A. KHAN TAHIRKHELI et al (Geology of Kohistan AND Adjoining EURASIAN AND INDO
PAKISTAN CONTINENT) conducted that Kohistan constitutes about 36000 square kilometers of
territory located between the Indo-Pakistan and Eurasian plates, on the northwestern tip of the
Himalaya. Earlier, Dasios (1964) has differentiated this part as a tectonic zone of Karakorum.
Bulk of Kohistan sequence consists of amphibolites, diorites, meta-norite (pyroxene-
granulite) and associated volcanic rocks which are considered to be the crust of an ancient calc-
alkaline island arc.
This sequence has been abducted on to the palaeozoic rocks of the Indo-Pakistan continent on the
south and subducted under the Eurasian platform along the northern mega shears.
The northern mega shear along Hini-Chalt-Yaseen-Drosh was formerly used to be considered
the only extension of the Indus suture west of Nanga Parbat. Recent studies by Tahirkheli et al
(1976,77) have brought to light a southern mega shear marked by the occurrence of ultramafic and
high pressure metamorphic rocks, called Main Mantle Thrust(MMT), which delineates the southern
contact of the Kohistan island arc and the Indo-Pakistan continent. This confirms the bifurcation of
the Indus suture into two suture zones, west of Nanga Parbat.
In this paper, an attempt has been made to introduce the geology of Kohistan island arc and
the adjoining Eurasian and Indo-Pakistan continents.
MATHEW P. WILLIAMS et al (Dept of Geology, Imperial College, London, SW7 2BP, U.K)
observed the gneisses, granites and meta sediments of the northern exposed margin of the Indian
plate in the Besham antifoam consist of a Precambrian crystalline basement with younger
sedimentary cover. These were metamorphosed during the main fabric-forming event of the
Himalayan orogeny, a ductile simple shear dominated deformation of the footwall of the MMT
during southward over thrusting of the Kohistan Arc. Deformation intensity and ductility decrease
southwards. Subsequent thrusting brought together internally imprecated blocks which have
different deformational metamorphic histories. High grade rocks thrust over low grade rocks within
each block define an inverted metamorphic gradient produced by post metamorphic thrusting.
Major cross folding producing the Besham antiform, plus brittle faults are expressions of the later N-
W directed back thrusting and N-W compression and uplift of the Besham area.
Geological survey of Pakistan reported that Northern areas of Pakistan, comprising Diamir
(Chillas), Gilgit, including Hunza and Nagar) Ghizar including (groups of Yaseen and ishkomem) and
Baltistan (Skardu district lies between latitude of 35 and 37 and longitude 72 and 77 E. It covers total
area of 6000 Rm2
and constitutes one of the highest mountain region of the world. The areas have
arranged topography with a very high relief some of place like Raka-poshi, Nanga-parbat and K2 are
famous worldwide for their elevation and gradient, Numerous peaks are perpetually snow-covered
and the area most extensively glacial outside three great mountains knees, the Karakorum,
Hindukush and Himalayas dominate thetopographic scenario of the region, Indus, Gilgit and Hunza
river along with their numerous tributaries drain the area.
Population is spare and restricted by irrigated plain amidst rugged ranges Gilgit, Chillas,
Hunza and Skardu is main district, all area suited on the world-famous Karakorum highway (KKH),
The KKH is metaled1 and all weather road, but temporary road block are common due to rock sliding
and mudflow.
The study area from a part of Kohistan terrain which sand witched between the Indian plate
to the south and Karakorum (micro continental) and Asian plates to the north.

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DAY I (STOP I)
Kamila Amphibolite:
it is a part of KIA.
It is form due to the product of intra oceanic subduction.
In this complex, there is amphibolite rock which has been intruded by a huge batholith of gabbro
and gabbro norite which is also known as chillas complex and due to this intrusion, this Kamila
amphibolite complex has been divided into two:
1) Southern Kamila amphibolite.
2) Northern Kamila amphibolite.
Now we are exactly observing the southern Kamila amphibolite which is extended up to lower Dir.
Amphibolite:
It is medium to high grade metamorphic rock which is composed of amphibole, biotite and calcic
rich plagioclase.
The shiny black color is biotite, white color is calcic rich plagioclase and the black color which do not
shines is amphibole.
Field identification of amphibolite:
✓ Dark black in color.
✓ Medium to high grade metamorphic rock.
✓ Coarse grained metamorphic rock.
✓ Composed of amphibole, biotite and calcic rich plagioclase.
Conclusion of Stop I: Here we study Kamila amphibolite which is divided into two parts.
Amphibolite is dark color rock which is coarse grained. It is composed of amphibole, biotite and
calcic rich plagioclase.
Field photography:

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Associated sketches:

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DAY I (STOP II)
Chamtalai Blue Schist:
• Blue schist is very low grade metamorphic rock form under very low temperature and high
pressure.
• Blue schist is a field recognition of convergent plate boundary.
• Blue schist has glaucophane which forms under high pressure and low temperature.
• Glaucophane is a blue amphibole.
• Glaucophane is needle like mineral.
• Blue schist also has pyrite which is also called Fool ‘s Gold.
• Protolith for blue schist is shale and basalt.
Based on blue schist geologist concluded that neo tethyan ocean (N.T.O) was subducted
beneath Kohistan Island Arc (K.I.A) and finally Indian plate collided with Kohistan Island Arc
(K.I.A) and form a suture zone by the abduction of ophiolites along main mantle thrust
(M.M.T).
Identification of Blue Schist:
✓ Blue color rock.
✓ Diagnostic mineral is blue color amphibole.
✓ Will be heavy due Fe Mg minerals.
✓ Coarse grain metamorphic rock.
Conclusion of Stop:
In this stop we study the blue schist which has glaucophane and pyrite. Glaucophane is a blue
amphibole while the pyrite is also called fool’s gold. Glaucophane is needle like mineral present in
blue schist. Blue schist form during high pressure and low temperature conditions so it is indication
of convergent plate boundary.
Field photography:

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DAY I (STOP III)
Shangla Top:
Dunite:
• Dunite is ultrabasic igneous rock, form in upper mantle or oceanic lithosphere.
• Dunite have more than 95% of olivine.
• Dunite is the first rock which crystalize at magma chamber.
• At surface of the earth dunite formation is not possible.
• Here dunite is present at surface which is a part of oceanic lithosphere, abducted along
MMT.

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Dunite
Identification of Rock:
✓ Coarse grained rock.
✓ Composed of 90% olivine so called olivinite.
✓ Granular, green igneous rock.
✓ It weathers to a dun brown color.
Serpentinite:
Dunite Serpentinite Talc Asbestos
• Serpentinite rock is greenish in color and give shiny appearance.
• And this green color is due to serpentine mineral.
• This rock also possesses calcic plagioclase or feldspar which is white in color.
• When alteration occur in dunite and the olivine of dunite reacts with water it
converts into serpentinite.
• Serpentinite have three polymorphs which are given below:
1) Antigorite: which is green in color.
2) Chrysotile: It is fibrous variety like a tree core. these are made due to high stresses.
Represent the shearing and tectonic activity.
3) lizerdite: it is a rare variety of serpentinite.
Identification in field:
✓ Serpentinite is greenish color.
✓ It possesses Shiny appearance.
✓ Possess calcic plagioclase or feldspar which is white in color.
Conclusion of stop III:
Here at this stop we study two types of rocks, serpentine and dunite. Dunite is ultramafic plutonic
igneous rocks form in oceanic lithosphere or upper mantle, here it is abducted along MMT and is a
part of oceanic lithosphere. It consists of 95% olivine. The second rock serpentinite is form when
water react with dunite. Its color is green due to mineral serpentine. There are three polymorphs of
serpentinite antigorite, chrysotile and lizardite.
Field photography:

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Day I (Stop IV)
Alpurai (Marghuzar FM)
Alpurai group have the following formations.
Older Swat Granitic Gneiss.
Marghuzar Formation.
Manglawar Formation.
Saidu Graphitic Schist / Saidu Formation.
Kashala Formation.
Younger Nikanai Ghar Formation.
• Age of marghuzar formation is Paleozoic.
• Marghuzar formation have marble.
• Marble is the metamorphosed form of limestone or dolomite.
• The formula of marble is CaCO₃
• It has Dolerite dyke in the form of igneous intrusions.
• It has mosaic texture in microscope and sugary texture.
• Muscovite and calcium carbonate is also present.
Field identification of Marble:
✓ Will possess a sugary texture.
✓ Its parent rock will be limestone.
✓ No bubbles will produce when we pour Hcl on it.
✓ Will possess medium to coarse grained calcite crystal.
Conclusion of stop IV:
Here it this stop we study the formation of alpurai group which is marghuzar formation. The main
lithology of marghuzar formation is marble in which muscovite mica is also present.

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Field photography:
Day I (Stop IV) (Belay Baba)
Manglawar formation:
• Manglawar formation consists of augen gneisses.
• When igneous rocks like granite is metamorphosed, it changes into gneisses.
• Here augen gneiss is present.
• Augen mean eye like structure present in rocks.
• There are two types of gneisses.
• Orth-gneisses and para-gneisses.
Orthogenesis:
When acidic and intermediate rocks metamorphosed under high grade metamorphism called
orthogenesis.
Protolith for this gneiss is granite, syenite
Para gneiss:
When metamorphism of sandstone and quartzite under high grade metamorphic condition
occur known as para-genesis.
Identification of gneisses in field:
✓ Will possess light and dark color alternate bands.
✓ Medium to coarse grained.
Here we study the manglawar formation which consists of augen gneisses. Gneisses have two types
ortho gneisses and para gneisses. Will possess light and dark color alternate bands. gneisses
are medium to coarse grained.

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Field photography:
Day II (Stop I)
Besham group rocks:
• The age of besham group rock is Paleozoic.
• Besham group rock consists of meta sedimentary rock which is intruded by syn-orogenic and
post-orogenic granitic bodies.
• Syn-orogenic granitic bodies are metamorphosed into augen gneisses.
• While post-orogenic granitic bodies are un metamorphosed and present in the form of
Lahore granite.
• Besham group rocks consists of two types of rocks.
I) Graphitic Schist.
II) Quartzite.
I) Graphitic schist:
• When black shale is metamorphosed, it changes into graphitic schist.
Black shale Graphitic schist
Field identification of graphitic schist:
✓ Fresh sample will turn your fingertips black.
✓ Having schistosity.
II) Quartzite:
• Quartz rich sandstone is called quartzite.
Field identification of quartzite:
✓ Quartzite is usually white to gray in color.
Augen gneiss

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✓ Hardness is 7 on MOH scale.
✓ Quartzite is a non-foliated metamorphic rock.
✓ the fresh surface of quartzite is rough and the grain is rounded.
Conclusion of stop I:
Here we study Besham group rocks which is of Paleozoic age. The besham group rocks is
composed of meta sedimentary rocks which is intruded by syn and post orogenic granitic bodies.
The syn-orogenic bodies are metamorphosed to augen gneisses during Himalayan orogeny while
the post orogenic bodies are un metamorphosed in the form of Lahore granite.
We study two types of rocks here. Graphitic schist which is form from the metamorphism of
black shale and is soapy in touch. When it is touched, it changes the fingers black. We also study
quartzite which is quartz rich sandstone.
Field photography:
Day II (Stop II):
Leuco-granite:
• Leuco mean white.
• White granite is called leucogranite.
• It has less amount of biotite that’s why its color is white.
Field identification of granite:
✓ Light color rock.
✓ Possess feldspar, biotite and quartz.
Conclusion of stop II:
Here we study granite which is white in color and have biotite, feldspar and quartz.

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Field photography:
Day II (Stop III):
Dubair Grano-diorite:
• Grano diorite is a plutonic igneous rock and it is composed of Fe Mg, Biotite minerals.
• Hornblende is also present in this rock which is a member of amphibole.
• The word grano diorite is derived from its physical appearance and chemical composition.
• It is in between granite (acidic plutonic rock) and diorite (plutonic intermediate rock).
• This rock has been metamorphosed and it was intruded in besham group of rocks as a
pluton or simply it is a part of besham complex or besham group of rocks.
Field identification:
✓ Granodiorite is a coarse-grained intrusive igneous rock
✓ Composed of quartz and plagioclase, Fe Mg, Biotite minerals.
✓ The hardness is 6.
✓ Contains more dark minerals than the granite.
Conclusion of stop III:
Here we study grano diorite. It is a plutonic igneous rock iron magnesium and biotite. The word
grano-diorite suggest that it is in between acidic plutonic rock and plutonic intermediate rocks
(granite and diorite). The hardness of rock is 6 and it is coarse-grained intrusive igneous rock.

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Field photography:
Day II (Stop IV)
jijal complex:
• It is composed of mantle rocks including chromite in the form of cumulates, dunite,
serpentinite, peridotite and some patches of pyroxenite.
• This is an ophiolitic sequence .it a welded zone between Indian plate and Kohistan island arc.
This complex is remnant of Neo-tethyan oceanic crust.
• Abduction of jijal complex suggests that there was an intervening ocean between Indian
plate and Kohistan island arc which was sub ducted completely in Eocene age.
• Jijal complex is composed of the following rocks:
1. Dunite.
2. Pyroxenite.
3. Chromite.
4. Serpentinite.
5. Hornblendite.
6. Peridotite.

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Chromite:
• Chromite is an oxide mineral composed of chromium, iron, and oxygen (FeCr2O4).
• It is dark gray to black in color with a metallic to submetallic luster and a high specific
gravity.
• It occurs in basic and ultrabasic igneous rocks and in metamorphic and sedimentary rocks
that are produced when chromite-bearing rocks are altered by heat or weathering.
✓ MOH hardness is 5.5 to 6.
✓ Heavy rock.
✓ Dark grey to black, rarely brownish in color.
Conclusion of stop V:
Here we study chromite which is heavy rock and its hardness is from 5.5 to 6. It is dark gray to black
in color with a metallic to submetallic luster and a high specific gravity.
Field photography:
Day II (Stop VI)
pyroxenite:
• Pyroxenite is an ultra-mafic igneous rock consisting essentially minerals of the pyroxene
group such as augite, hypersthene, bronzite or enstatite.
• Pyroxenite is a type of intrusive igneous rock that is predominantly composed of pyroxenes.

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✓ Pyroxenite is an ultramafic igneous rock.
✓ Coarse Grained Rock, Opaque Rock.
✓ Color ranges from black to Grey, bluish - grey, dark greenish - grey, green, light greenish
grey.
✓ Predominantly composed of pyroxenes.
Conclusion of stop VI:
Here we study pyroxenite which is coarse grained opaque rock. Color is from black to Grey, bluish -
grey, dark greenish - grey, green, light greenish grey. It is composed of pyroxenes.
Field photography:
Day II (Stop VII)
Hornblendite:
• Hornblendite is a plutonic rock and composed of more than 90% hornblende mineral.
• This mineral is a member of amphibole and the color is black.
Field identification of hornblendite:
✓ A granular igneous rock
✓ Composed almost entirely of hornblende.

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Conclusion of stop VII:
Here we study hornblendite which is granular igneous rock, composed of almost entirely of HB. Its
color is dark black.
Field photography:
Day II (Stop VIII)
Here we study three types of rocks.
I) Pyroxene granulite.
II) Hornblendite.
III) Almandine garnet.
• When gneiss is metamorphosed, it changes into granulite.
• Granulite is very high grade metamorphic rock.
• These rocks which is present here is a part of Kamila amphibolite belt.
• Protolith for these rocks is igneous basalt.
• Pink color almandine garnet is also present here.
Field identification of hornblendite:
✓ A granular igneous rock
✓ Composed almost entirely of hornblende.

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Conclusion of stop VIII
Here we study hornblendite, pyroxene granulite and almandine garnet. Granulite is very high grade
metamorphic rock. These rocks which is present here is a part of Kamila amphibolite belt. Protolith
for these rocks is igneous basalt. The color of almandine garnet is pink.
Field photography:
Day II (Stop IX)
Z or S type folds:
Z or S type of folds shows fault or shear zone.
The two folds are made in opposite directions which forms a shape that resembles the letter Z.

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Field photography:
Day III (Stop I)
Chillas Gabbro Norite:
• The type locality of gabbro norite is Chillas town.
• Gabbro norite is composed of amphibole group mineral mostly hornblende.
• Calcic plagioclase ortho- pyroxene biotite and silica is also present.
• The Chillas complex has been intruded in Kamila amphibolite.
• Chillas complex is the world largest gabbro norite batholith.
• This complex is a pre-orogenic batholith.
• The age of this intruded batholith is younger then Kamila amphibolite.
• This intrusion divide the Kamila amphibolite into two parts.
I) Northern Kamila Amphibolite.
II) Southern Kamila Amphibolite.
Field identification of gabbro norite:
✓ Gabbro norite is dai-basic rock means intermediate to basic.
✓ composed of 45-55% silica.
✓ Composed with dominant composition of of calcic rich plagioclase.
✓ Composed of main three minerals as 1: Feldspar 2: Amphibole 3: Biotite.
Conclusion of the stop:
Here we study gabbro-norite which is Composed of main three minerals as Feldspar, Amphibole,
Biotite. It has 45 to 55% silica.

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Field photography:

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Day III (Stop II)
Active fault (Raikot Fault):
• Raikot fault is a strike slip fault.
• Lies on the western limb of Nanga Parbat.
• We observed tilting of strata in recently deposited sediment which are due to the
stresses of an active fault as raikot fault.
Field identification of active faults:
✓ Tilt or inclination of sediments is the only criteria for identification of active fault in
field.
Conclusion of stop II:
Here we study fault which is active fault. The name of the fault is raikot fault which Lies on the
western limb of Nanga Parbat. Here we also study the tilting of beds which is the
characteristics of the active fault.
Field photographs:
Day III (Stop III)
Fault rocks/mylonites/fault gorge:
• it is a fine grained metamorphic rock.
• It is banded.
• It results from the grinding or crushing of other rocks.
• Classification is based on texture.
• Fault breccia is angular.

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Conclusion of stop VI
Here we study mylonites which is fine grained metamorphic rock form due to grinding or crushing of
other rocks.
Field photography:
Day III (Stop IV)
Gneisses:
• it is a part of besham group rocks (northern Kamila amphibolite belt).
• It has hornblende pegmatite which is black in color while garnet which have brown color.
• There are two types of gneisses.
• Orth-gneisses and para-gneisses.
Identification of gneisses in field:
✓ Will possess light and dark color alternate bands.
✓ Medium to coarse grained.
Here we study the manglawar formation which consists of augen gneisses. Gneisses have two types
ortho gneisses and para gneisses. Will possess light and dark color alternate bands. gneisses
are medium to coarse grained.

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Field photography:
Day III (Stop V)
Kohistan Batholiths:
• Much of the Kohistan batholiths appear to be the product of mantle wedge above
subduction zone but some of the leuco-granite and aplite seems to be derived from the
partial melting of crust of Kohistan arc.
• One of the largest igneous body which covers the central and northern part of KIA. It covers
more than 2700km in length.
• Kohistan batholiths are exposed in the geology of Pakistan through exhumation process and
have three genetic phases that are:
1) Pre-genetic.
2) Sin-genetic.
3) Post-genetic.
Pre-genetic:
• Pre means before and genetic means orogenic process so these are those batholiths which
forms before orogenic process is known as pre genetic batholiths.
• Pre-genetic Kohistan batholiths are formed before the development of Kohistan island arc.
• These are highly deformed and metamorphosed due the stresses and temperature is the
product of convergent plate boundary and collision of two plates.
• Here in this type of batholith there is a mesoscopic structure.
✓ Pre - genetic batholiths is of dark color.
✓ Older than sin genetic.
✓ Possess mesoscopic texture.
✓ Metamorphosed and as well deformed.
✓ Intruded by syn- genetic batholiths.

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Syn-genetic:
• Syn means during and genetic means orogenic process so these are those batholiths which
were formed during orogenic process of Kohistan island arc is known as sin genetic.
• These sin genetic batholiths are intruded in pre-genetic batholith which clearly indicates that
pre-genetic batholiths are older than the sin-genetic batholith and this has been interpreted
by cross cutting relationship.
• These Batholiths are metamorphosed but these are not deformed.
✓ Syn- genetic batholiths are less dark than the pre-genetic.
✓ These are younger than the pre-genetic batholiths.
✓ Metamorphosed but not deformed.
Post-genetic:
• Post means after and genetic means orogenic process so these are those batholiths which
are formed after orogenic process of the Kohistan island arc is known as post genetic.
• Post genetic Kohistan batholiths are formed after the development of Kohistan island
genetic.
• These batholiths are neither metamorphosed nor deformed.
✓ Light color which is also known as leucogranite, leuco means white and plagioclase rich.
✓ Not deformed nor metamorphosed.
Conclusion of stop V:
Here we study three types of batholiths which is called Kohistan batholith. Pre - genetic batholiths is
of dark color and is older than sin genetic. Syn- genetic batholiths are less dark than the pre-genetic
and are younger than the pre-genetic batholiths. Light color which is also known as leucogranite,
leuco means white and plagioclase rich and are not deformed nor metamorphosed.

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Field photography:
Day III (Stop VI)
Chalt Volcanos:
This complex is composed of three types of volcanic igneous rocks that are:
a) Rhyolite
b) Andesite
c) Basalt
(a) Rhyolite:
• Rhyolite is an acidic igneous volcanic rock composed of more than 65% of silica.
✓ Felsic rock having composition of silica is more than 65%.
✓ Light color.
✓ Coarse grain because it is extrusive rock.
✓ Equivalent rock for rhyolite is granite.

30 | P a g e
✓ Composed of alkali feldspar and igneous quartz.
(b) Andesite:
•
Andesite is an intermediate igneous volcanic rock having 55-65% silica and have FeMg
minerals.
✓ Greenish color rock.
✓ Intermediate composition.
(c) Basalt:
• It is basic volcanic igneous rock which possess 45-55% of silica. Because of pillow structure it
is also known as pillow Basalts.
• When eruption occur in basin so basalt have FeMg minerals so for his mineral high pressure
and temperature required but FeMg minerals cools quickly and forms pillow structure.
• These rocks are metamorphosed during Himalayan orogeny, there also known as meta-
volcanic rocks.
✓ Dark color
✓ Fine grained
✓ volcanic rock.
✓ Possess pillow structure.
Conclusion of stop VI:
Here we study basalt which is fine grained and dark in color. It is a volcanic rock.
Field photography:

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Day III (Stop VII)
Nagar Pillow Basalt:
• It is form on columnar basalt.
• It is less preserved because of metamorphism.
• It is a part of ophiolite sequence.
Field Identification of basalt:
✓ Dark color
✓ Fine grained
✓ volcanic rock.
✓ Possess pillow structure.
Conclusion of the stop:
Here in this we observed rocks which belongs to the chalt volcanic complex which was composed of
basalt, andesite, and rhyolite. this complex lies on the leading edge of Kohistan island arc and
formed due to subduction. Here in this complex the magma was same but the rocks are
different because of episodic volcanism. Here we also observed pillow structure in basalt
due to which this rock is also called pillow basalt. These structures were formed due to the
rapid cooling of FeMg minerals in water.

32 | P a g e
Field photography:
Day III (Stop VIII)
Here we study three types of rocks.
I) Talc schist.
II) Pyroxenite.
III) Serpentinite.
• It is a suture zone between KIA and Eurasian plate called MKT.
• The zone is called shyoke suture zone.
• It is a convergent plate boundary.
Field identification of Talc:
✓ light, whitish, creamy in color.
✓ Host rock for emerald.
✓ Gives soapy touch.
Identification of pyroxenite:
✓ Pyroxenite is an ultramafic igneous rock.
✓ Coarse Grained Rock, Opaque Rock.
✓ Color ranges from black to Grey, bluish - grey, dark greenish - grey, green, light greenish
grey.
✓ Predominantly composed of pyroxenes.
Field identification of serpentinite:
✓ Greenish color.
✓ Shiny appearance.
✓ Possess calcic plagioclase or feldspar which is white in color.

33 | P a g e
Conclusion of stop:
Here we study three types of rocks, talc schist which is the soapy in touch and have hardness
one. We also study serpentinite and pyroxenite on this stop. We also study pyrite mineralization.
The important thing of this stop is we study MKT which is a boundary between Eurasian plate
and KIA, this zone is called shyoke suture zone. This boundary is convergent plate boundary
which is form by the convergence of paleo-tethyan ocean.
Field photography:
Day IV (Stop I)
Hunza marble:
• When limestone is metamorphosed, it changes into marble.
• Hunza marble is deposited on the southern continental shelf of Eurasian plate.
• In hunza marble golden color mica, ruby and calcite is present.
• Hunza marble is famous for Ruby all over the world.
Field identification of marble:
✓ Will possess a sugary texture.
✓ Its parent rock will be limestone.
✓ No bubbles will produce when we pour Hcl on it.
✓ Will possess medium to coarse grained calcite crystal.
Conclusion of stop I:
Here we study marble which has sugary texture. It is white in color and form due to metamorphism
of limestone or dolomite.

34 | P a g e
Field photography:

35 | P a g e
Day IV (Stop II)
Passu slates:
• when shale or basalt is metamorphosed, it changes into slate.
• If protolith is igneous then slate form will be spotted slate.
• Slate is a fine-grained foliated metamorphic rock derived from an original shale-
type sedimentary rock composed of clay or volcanic ash through low grade regional
metamorphism.
• This rock possesses lineation. It is the finest grained foliated metamorphic rock.
Identification of slates in field:
✓ Slates are grey in color.
✓ fine-grained.
✓ Contain abundant quartz and small amounts of feldspar, calcite, pyrite, and
hematite.
✓ Finest grained foliated metamorphic rock.
✓ Possess lineation.
Conclusion:
Here we observed a fine-grained rock it was grey in color which possessed foliation or
lineation. This rock was slate which is a metamorphic rock form from by the metamorphism of shale.
Slate can also be form by the metamorphism of basalt and that slate is called spotted slate.
Field photography:

36 | P a g e
Outcome:
This area is composed of minerals like Olivine, serpentine, antigorite,lhezerdite crysotile, granitic
genesis. Here Saidu formation and Kashala formation and marghazar formation of Triassic age and
blue schist are present. Ongoing further to the north i.e. Besham groups rocks like chillas formation is
present in Kohistan Island Arc Complex.
Jijal complex is the important part of the K.I.A containing mafic and ultra-mafic composition and which
are divided into two groups:
❖ Group1: Alpine type rocks.
❖ Group2: Garnet granulite.
Chillas complex is intruded in the middle of Kohistan island arc. Youngest thrust which is still active
called raikot fault/ raikot thrust fault. It is an active thrust fault on the western flank of the Nanga
parbat, more than 45 minor earth quacks have been reported per day.
Kohistan batholith is present there which is the beauty of that area and is the largest igneous
body in the whole world covers the central and northern part of Kohistan island arc complex. The
pillow structure basalt is the dominant clue that subduction has been occur of paleo tethyan plate
beneath Eurasian plate.
Melange zone is associated with M.K.T /suture zone is called rakaposhi ophiolitic melange
zone.
References:
• Lectures of Sir Imran Ahmad.
• Physical Geology book by Plummer
• Geology of Pakistan edited by F.K.Bender and H.A.Raza
• Geology of Pakistan Book by Kazmi and jan.
• Stratigraphy of Pakistan by S.M. Ibrahim shah.
• www.Geology.com
• https://en.wikipedia.org/wiki/Geology_of_Pakistan.
• allaboutgeology.blogspot.com/2011/04/stratigraphy-of-pakistan.html

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