Field Report Of Attock-Cherat Range PDF.pdf

7/24/2019 Field Report Of Attock-Cherat Range PDF.pdf

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STRATIGRAPHIC STUDY OF ATTOCK-CHERAT RANGE

BY

Muhammad Aslam Khan

Report Submitted To Muhammad Awais Lecturer GeologyDepartment, University Of Swabi.


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Introduction

The Attock-Cherat Range is divided into three east-west trending blocks that are bounded

by thrust faults. From north to south these are listed as Northern Block with unfossiliferous

argillite, slate, phyllite and limestone of Precambrian age intruded by dolerite sills and dykes; thecentral block comprising unfossiliferous flysch of Precambrian age and overlain by Jurassic,

Cretaceous, Paleocene, Eocene, Miocene rocks, and the Southern Block consisting of

unfossiliferous limestone, dolomite, argillite and quartzite overlain by Tertiary sequence similar

to that found in Central Block (Yeats and Hussain). The rock sequence in the southern part of the

mapped area includes an extension of the main Kala-Chitta Range.

Station # 1

In station 1, the sequence of rocks were consist of conglomerate and slate s of Manki

Formation. The conglomerate was in contact with slates and the contact was unconformable. The

conglomerate was on the top of slates. On the basis of GPS data ( 3352'50.60" N and 7213'47.20"

E) satellite image of the study area is shown in figure-1 and a field image in figure-2.

Figure-1: Satellite image of the study area.

River Indus


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Figure-2: Field image of study area (camera facing west direction and men are for scale).

These conglomerates are formed by consolidation and lithification of gravel. Conglomerate

present there was consisted of cobbles, pebbles, granules and large blocks of allochthonous

limestone. Large blocks of limestone present in the conglomerate were so near to each other which

can be seen in figure-3.

Figure-3: Limestone blocks in conglomerate (camera facing west direction, men are for scale).


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Structural Features

On the way to station 2 , there was mud cracks which is a sedimentary structure, these

are polygonal shaped cracks formed when mud was dewatered, shrink and leaves the cracks. This

tells that mud was saturated and then expose to air. They are also called as desiccation cracks. Mudcracks are shown in figure-4. The next structural feature was Chevron fold; a fold with sharp

angular hinge and planar limbs of equal length. The inter-limb angle in chevron fold is generally

up to 60 degrees. Chevron fold is shown in figure-5.

Figure-4: Mud cracks (bottle is for scale).

Figure-5: Chevron fold (camera facing west direction, geological hammer is for scale).


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Station # 2

In station 2, there was an anticline in Darwaza limestone in which one limb was dipping

towards the north direction and other towards the south direction. Argillites were present on top

of the limestone. Limestone was in grey color and thick bedded while argillite was yellowish- brownish color and thin bedded. On basis of GPS data (3351'46.60" N and 7214'00.60" E)

satellite image of the study area is shown in figure-6 and a field in figure-7.

Figure-6: Satellite image of the study area.

Figure-7: Study area (camera facing east direction).


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Strike and Dip

The strike and dip data measured in the field is given in the following table:

Strike

095100

170

120

135

125

130

145

135

133

Dip

7067

44

50

85

68

70

58

66

57

Sense

SS

SW

SW

SW

SW

SW

SW

SW

SW

The strike and dip data plotted on stereonet is shown in figure-8.

Figure-8: Picture showing strike and dip.

Field Report Of Attock-Cherat Range PDF.pdf

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