The document discusses the geography, geology, seismicity, volcanism, and magmatism of the Kohistan Island Arc (KIA) in northern Pakistan. It defines an island arc as a long, curved chain of oceanic islands associated with volcanic and seismic activity during subduction and orogenesis. Island arcs form when subducted slab material melts and rises, erupting as volcanoes, or from mantle plumes or hot spots. The KIA formed in the early-middle Cretaceous period and is divided into southern, central, and northern parts consisting of different rock complexes and batholiths. The area experiences frequent earthquakes from seismic activity and volcanism from magma rising and erupting at the surface

1. Submitted By:. Syed Rasib Naqvi
Submitted To:. Dr Raja Jahanzaib Sab
Roll #:. 26
Class:. 7th Semester (Mor)
Session:. 2013-2017
Subject:. Geotectonics
Topic:. Geography Geology Of Island
Arc(K.I.A) Seismicity,
Volcanism,and Magmatisma

2. What is Island arc?
Ans :. Long, curved chain of oceanic islands
associated with intense volcanic and seismic activity
and orogenic processes. Destructive earthquakes
occur frequently at the site of island arc.

3. Island Arc Formation
There are two ways in which a group of islands can form.
1.) As a lithospheric slab is being subducted, the slab melts
when the edges reach a depth which is sufficiently hot. Hot,
remelted material from the subducting slab rises and leaks
into the crust, forming a series of volcanoes. These volcanoes
can make a chain of islands called an "island arc".
2.) The second way in which islands are formed is via
plumes or hot spots in the lithosphere.

6. Geography of K.I.A
Kohistan island arc is situated in northern
Pakisitan, to the west of the high Himalaya
crystalline wedging body, the southern and northern
boundary is MMT and MKT.
Kohistan is a c. 30000 square km

7. Age of K.I.A:.
 early-middle Cretaceous period
 This was active some 30 million years before collision
Division of K.I.A:.
1. Southern part
2. Central part
3. Northern part
Southern part:.
The southern part is further divided into following
1. Jijal complex
2. Komila amphibolite
3. Chilas complex

8. Central part of K.I.A:.
Central part consist of kohistan batholith.
Northern and western part of K.I.A:.
The northern and western part of K.I.A consist of
volcanic and Metasediment.

10. Seismicity:.
 The worldwide or local distribution of earthquakes in
space, time, and magnitude.
Volcanism:.
 volcanism is the process in which magma rises
through Earth’s crust and issues forth at the surface as
lava flows and/or Pyroclastic materials and gases.

12. Magmatism:.
 Magmatism is the only true endogenic process
for generating new material on the earth
surface.
 Megmatism is the formation of igneous rocks
from magma.

13. THANK YOU