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GEOLOGY AND STRUCTURE OF PIR SOHAWA,
SANGADA, & SHADARA AREA, ISLAMABAD,
MARGALA HILLS AND MICROFACIES ANALYSIS OF CHORGALI FORMATION
Muhammad Wajid Manzoor
Roll No 09
Institute of Geology
University of the Punjab Lahore
PHYSIOGRAPHY OF THE PROJECT AREA
Introduction
Objectives of work
Climate
Vegetation
Mountains
Soils
Drainage Pattern
Valleys
Nullah Gravels
Terraces
Population
Map of study area (Goggle Earth).
Project area on toposheet 43G/1
Vegetation in study area
Valleys in Study area
TECTONIC FRAMEWORK OF PAKISTAN
Introduction
o Geographically Pakistan is located at the west of South Asian Subcontinent.
o Pakistan comprise of three tectonic plates and its major portion lies on the Indian
Plate.
Historical Background
• Pangea Breakage
• Location of Indian Plate in Gondwanaland
• Northward drift and Rotation of Indo-Pakistan Plate
• Schematic diagram of continents
spreading • Relative positions of the continents
from 225 m.y to the present
• Position of India’s plate in
Gondwanaland
• Different positions of the Indian Plate with
respect to time during Northward drift
from 71Ma to present position.
TECTONIC ELEMENTS OF PAKISTAN
Himalayas consist on series of Southward propagating thrust sheets that are
formed by the Collison of Indian and Eurasian Plates. Continuous collision creates
younger thrust towards south (Searle et al., 1997).
These thrusts are described as:
o Main Karakorum Thrust
o Main Mantle Thrust (MMT)
o Main Central Thrust (MCT)
o Main Boundary Thrust (MBT)
o Himalayan Frontal Thrust (HFT)
DIVISION OF HIMALAYAS
The closing and subduction of the Tethyan Ocean was followed by collision of
continents that produced different structures and mountain ranges like Himalayas
(Genser, 1964).
Himalayas form a 2,500 km long and 160-400 km wide range that surround the
Indian subcontinent.
The geology of Himalayas is quite complicated that start from sedimentary
sequence of Phanerozoic to Eocene.
Genseer (1964, 1981) and Wadia (1964) has divided Himalayas from north to
south into following divisions:
o Tethyan Himalayas
o Higher Himalayas
o Lesser Himalayas
o Sub-Himalayas
LITHOSTRATIGRAPHY OF STUDY AREA
The stratigraphic succession of study area consists of Mesozoic to Tertiary sedimentary rocks.
The lower Jurassic Datta Formation is not exposed here.
The Kawagarh Formation of Cretaceous age is also missing in study area.
In study area Hangu formation unconformably overlies the Lumshiwal Formation.
Formation Lithology Age Environment
Murree Formation Rddish to maronish sandstone having epidot mineral Early Miocene Fluvial
Kuldana Formation Variegated shale with marl and sandstone. Early to Middle Eocene Coastal plain tidal flat and brackish water.
Chorgali Formation Flaggy limestone with interbedded shale and marl. Early Eocene Lagoonal.
Margala Hill Limestone Limestone with intercalation of shale and marl. Early Eocene Shallow marine.
Patala Formation The greenish grey shale. The shale has splintery as well as blocky in nature. Late Paleocene Shallow marine, Lagoonal and outer shelf.
Lockhart Limestone Grey to medium grey, medium to thick bedded nodular limestone
containing Lockhartia.
Middle Paleocene Restricted, shallow marine embayment, shelf facies.
Hangu Formation Laterite band and White, light grey and reddish-brown medium to coarse
grained sandstone consisting chiefly of quartz.
Early Paleocene Very shallow marine and deltaic.
Unconformity
Lumshiwal Formation Greenish grey rusty brown glauconitic sandstone containing oyster shells. Lower Cretaceous Shore face and shallow marine deltaic.
Chichali Formation Black to light grey shale containing Belemnite. Late Jurassic to Early Cretaceous Restricted anoxic.
Unconformity
Samana Suk Formation Grey to medium grey limestone with dolomitic patches. Middle Jurassic Shallow marine.
Base not exposed
Smamana Suk Formation
Chichali Formation
Lumshiwal Formation
Hangu Formation
Lockhart Limestone
Patala Formation
Margala Hill Limestone
Chorgali Formation
Kuldana Formation
Murree Formation
STRUCTURE OF THE PROJECT AREA
The Sangada area is covered by rocks of Mesozoic-Cenozoic age.
That have undergone severe deformation during Himalayan orogeny demonstrated by
the development of mostly southeast verging faults and associated folds.
In addition to Margala Hill Limestone and Chorgali Formation, Lockhart Limestone
is commonly the most exposed oldest formation in most of the area.
Most of the faults are reverse, although some normal faults are also present.
The folds are predominantly Synclinal to Anticlinal.
The general trend of the outcrops is NE-SW, which is almost similar to trend of
overall Hazara Basin.
A brief description of the major structures follows:
o MBT:
MBT is passing in the south east of the mapped area near Shahdara village.
It is deeply dipping fault having NW-SE orientation.
This fault brings the older Samana Suk Formation in direct contact with Lockhart
Limestone.
o Ajwa Fault 1:
It is the SE dipping high angle fault, Which is present between Patala shale of Paleocene age and Chorgali Formation of Eocene age.
Extended downward between Lockhart Limestone and Chorgali Formation.
o Ajwa Fault 2 :
It is present between Patala shale and Chorgali Formation.
This fault dislocates the Patala shale, Margala Hill Limestone and ChorgaliFormation above the fault plane.
o Sangada Fault 1:
This fault is present between Chorgali Formation and Patala shale.
It runs SW-NE from Sangada area toward Kharian and up to the southwest of Nelaan
Bhota.
o Sangada Fault 2:
It truncates the Lockhart Limestone and splays of Mukhuial Faults with NW trending.
The dip angle of the fault is 450 NW.
o Makhuial Thrust 1:
The Makhuial Thrust 1 is trending SW-NE from Makhuial Peak running in the south
of Hariala toward Botha area.
The Paleocene Lockhart Limestone thrusted over Margala Hill Limestone of Eocene
age.
o Makhuial Thrust 2:
It is present between Patala shale of Paleocene age and Chorgali Formation of Eocene age with the same trend as that of Makhuial thrust 1.
o Hariala Fault:
This fault is present between Chorgali Formation and southeastern limb of syncline
within Lockhart Limestone, whereas Chorgali Formation above the fault plane moves
downward forming the normal fault.
o Khumal Gali Fault 1:
Margala Hill Limestone /Lockhart Limestone.
This is ENE trending fault dips northwestward with an angle of the dip is 600
o Khumal Gali Fault 2:
This fault is between Lockhart Limestone and Chorgali Formation.
Chorgali Formation is the upthrown block, above the fault plane.
o Khumal Gali Fault 3:
This fault is present between Kuldana Formation and Lockhart Limestone.
The fault is dipping to NW. The dip angle is 450.
o Khumal Gali Fault 4:
This fault is present between Lockhart Limestone and Chorgali Formation.
It is dipping at an angle of 430 to northwestward direction.
o Khumal Gali Fault 5:
It is present between Chorgali Formation and Patala Shale.
Its trend is ENE and it is dipping toward NW with an angle of 450.
o Ranias Synclines:
These are the two major synclines of Ranias area.
This important synclinal structure of the area extends NW-SE, northward from MBT toward Ajwa Restaurant.
The core of the syncline is comprising of lenses of Patala shale which is flanked by older formation, Lockhart Limestone.
o Ranias Anticlines:
Ranias anticline 1 and 2 are the subordinate anticlinal structure with two major synclines.
The Lockhart Limestone is present in the core of these anticline.
The trend of the anticlines is NW-SE.
o Sangada Syncline:
Sangada syncline is NW-SE trending major synclinal structure between Chorgali
Formation and Kuldana Formation.
The lens of Kuldana Formation is forming the core of the syncline.
o Hariala Synclines:
Hariala syncline is the NW-SE trending syncline, predominantly in Lockhart
Limestone.
The Patala shale is present in the core of the syncline in the form of lenses.
The SE limb of syncline 1 has faulted contact with Chorgali Formation.
o Hariala Anticlines:
The small anticlinal structures appear in a small depression (gali), with NW-SE
trend.
These anticlines are explained as the older formation Lockhart Limestone is
present in the core, above which younger Patala shale is present.
Map of the project area and cross
secession line A to A'
Cross sectional view of mapped area
from latitude longitude 33050'15'',
7307'00'' to latitude longitude
33047'13'', 7308'30''.
PALEOECOLOGY AND MICROFACIES ANALYSIS
o Paleoecology is the study of interactions between organisms and/or interactions
between organisms and their environments across geologic timescales.
o The dedicated study of past environments by studying the fossil records of
organisms that lived in that environment at the time (Wilson, 1975; Hottinger,
1998; Flugel, 2004).
o Therefore, paleoecologic analysis derives from two sources, fossils and associated
rooks.
Aim of Paleoecology:
o The aim of paleoecology is therefore to build the most detailed model possible of
the life environment of previously living organisms found today as fossils.
o Qualitative and quantitative foraminiferal analysis provides a high-resolution
database for the biostratigraphy and determines the main paleoenvironmental
parameters.
Observed Fauna:
o The protozoan most commonly observed as fossils are foraminifera.
o Foraminifera are found in all marine environments, from the intertidal to the
deepest ocean trenches, and from the tropics to the poles, but species of
foraminifera can be very particular about the environment where they
live(Flugel,2004).
The observed fauna includes the following :
o Nummulites
o Lockhartia
o Ostracodes
o Miliolid
Microfacies analysis
o Microfacies refers to the criteria appearing in thin section under microscope.
o Every facies of a deposition show well-defined petrographic, and paleontological properties which can be clearly differentiated from the properties of other facies in the same geological period.
Methodology:
Observed Facies:
o Bioclastic mudstone
o Bioclastic Wackstone
o Bioclatic Packstone
o Bioclastic Grainstone
Ramp facies:
Ramp facies reflect the protracted offshore energy gradients which are a
consequence of gradual water-depth change. Individual ramp depositional zones
differ strongly in their facies compositions (Burchette and wright 1992).
These facies are divided into the following:
o Inner ramp deposits
o Mid ramp deposits
o Outer ramp deposits
Conclusion
Based on field observations, Microfacies analysis of the Chorgali Formation in the
study area divided into four microfacies that are:
1. Bioclastic Mudstone
2. Bioclastic Wackestone
3. Bioclastic Packstone
4. Bioclastic Grainstone.
Microfacies analysis and sequence stratigraphic concept, the Chorgali Formation
was deposited in an area of low rate of subsidence, where the major controlling
factor is eustasy.
The Chorgali Formation is deposited in Inner to mid ramp.
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