STRUCTURAL INVESTIGATION OF A PART OF EASTERN SALT RANGE USING GIS/RS NEAR DOMELI TOWN, PUNJAB, PAKISTANUMER KHAYAMWAQAS NAWAZJODUT REHMANSOHAIL FAREEDBABAR SADDIQUE

OVERVIEW Our thesis area is located in the eastern part

of the Salt Range Salt Range encompasses the southern

portion of the Potwar Plateau This plateau is bounded on the east and west

by Jhelum and Indus rivers respectively and in the north by Main Boundary Thrust

Our area comprised of majorly Eocene to Miocene and Pliocene stratigraphy with structures heavily influenced by the complex tectonic history of the whole plateau

Geological map of the eastern Salt Range and Potwar Plateau modified after Jaswal et al. (2002).

POTWAR PLATEAU

M.B.T.

Dhurnal Fault

S.R.T.

Study Area

Geological map of the eastern Salt Range and Potwar Plateau modified after Jaswal et al. (2002).

POTWAR PLATEAU

• The Southernmost part of the Potwar Plateau• Formed as a result of ramping up of a basal decollment in the Pre Cambrian Salt Range Formation• According to Baker (1988), the eastern Salt Range exhibits the geometry of a fault bend fold

Geological map of the eastern Salt Range and Potwar Plateau modified after Jaswal et al. (2002).

POTWAR PLATEAU

• Limited by the Salt Range in the south and Soan Backthrust in the north• Developed first as an autochtho- nous part of Himalayan foreland Basin• Later on transformed into a piggy back basin when its own basal decollement was activated (Lillie et al; 1997)

Geological map of the eastern Salt Range and Potwar Plateau modified after Jaswal et al. (2002).

POTWAR PLATEAU

• A narrow zone between Main Bo- undary Thrust in the north and Soan Backthrust in the south• At surface it is mainly covered by the Murree Formation of Miocene Age• Siesmic interpretation suggest that a stack of imbricated thrusts is present underneath (Jaswal et al; 1997)

LOCATION OF THE STUDY AREA

N5 Highway

Dina12 km NW

METHODOLOGY The mapping technique we used was Remote

Sensing to reconfirm the Points of Interest in the field

Area co-ordinates were plotted in the Google Earth software and boundaries were drawn

The area marked in the Google Earth was then transferred into Global Mapper, a GIS software

Digital Elevation Modelling (DEM) method was used to generate a contour map of the area. Furthermore, this method was also incorporated while drawing the profile line for the cross sections

METHODOLOGY All the important contacts and structural

features were marked in the field, orientation noted, and saved in the GPS device as Points of Interest (POI’s)

Later on these POI’s were transferred to Google Earth software on the marked area along with the description

On Global Mapper the orientation related to each POI is plotted and the structures are demarcated

POI’s with similar information on different traverses were joined together in the Google Earth along with the additional visual aid of the color of formations

METHODOLOGY After a final trace out of the map is

completed in the Google Earth with the contacts, fold axis, faults and other minor structures marked, it is finally drawn in any graphical software (Corel Draw for instance)

For cross sections, DEM was used to generate the profile line and the formations were plotted with their respective contacts and orientations

Some of the graphics in the whole process are presented in the coming slides

DIGITAL ELEVATION MODELING (DEM)

Digital Elevation Modeling (DEM) of the study area. Black dots (POIs) show the measuring stations in the field. Different heights are represented by their respective colors in the scale.Orange lines mark the outline of our study area

Generated by:Global Mapper V. 12

TRAVERSES ALONG WITH POI’S

Area Square

Google Earth image of the study area. Outline of the area has been geographically referred by using GPS field data. Pins (POI) show the measurement stations in the field while the yellow lines are the traverses

REGIONAL TECTONICS SUMMARY

Map of Northern Pakistan showing subdivisions of Himalayas. Modified after Coward et al, 1988.Inset represents the study area

STRATIGRAPHY OF THE AREA

Stratigraphic column of the study area

Illustration showing the limestoneof Chorgali Formation

Illustration showing the sandstone ofthe Murree Formation

Illustration showing the purplish conglomerateand reddish sandstone of the Kamlial Formation

Illustration showing grey-green sandstone and pinkish clays of Chinji Formation

Illustration showing the sandstone of NagriFormation

Outcrop of clays in the Dhok Pathan Formation. In pre-set alternate sandstone and

clays can be seen

STRUCTURAL GEOLOGY The study area lies at the eastern extension of

the Salt Range and mostly represents northeast-southwest trending ridges showing northwest-southeast compression

Since the study area represents the eastern portion of SRT (Salt Range Thrust), this thrust has deformed the area to various extents

From south to north, the major structures controlling the subsurface geometry are as follows;

Kalra Thrust Domeli Thrust Kalra Anticline Domeli Anticline Pamaal Back Thrust

GEOLOGICAL MAP OF THE AREA

KALRA ANTICLINE While traversing from south to north in the

study area, the first major structure encountered in the southern part of the area is the Kalra Thrust

Along this thrust the older Chinji Formation of late Miocene age is thrusted over the younger Dhok Pathan Formation of Late Pliocene age

The hanging wall thus contains Chinji Formation and the Dhok Pathan Formation lies in the foot wall

The Kalra Thrust strikes S52oW with dip direction of 20oNW and its dip ranges from 70o to 75o

KALRA ANTICLINE

Photograph showing the Kalra Thrust between Moicene Chinji Formation and Pliocene Dhok Pathan Formation (northwest view)

DOMELI THRUST Along this thrust, the rocks including Murree

Formation of the Early Miocene age and the Eocene Chorgali Formation (representing Oligocene unconformity) are thrusted over the Late Miocene Chinji Formation

Murree Formation and Chorgali Formation thus occur along the hanging wall and Chinji Formation lies in the foot wall portion

This thrust is northeast-southwest oriented with numerous undulations and bends representing dip amount of 85o to 87o

DOMELI THRUST

Photograph showing the Domeli Thrust between Chinji Formation and Murree Formation (northward view)

KALRA ANTICLINE This anticline occurs to the north of the

Domeli Thrust. It is a major anticline in the area exposing Chorgali Formation in its core

Its southern limb coincides with the Murree Formation along the Domeli Thrust. Chorgali Formation is folded because of the Domeli Thrust

The trend of the hinge line of the fold is 2250 and it plunges westward; coinciding with the Pamaal backthrust

KALRA ANTICLINE

Photograph showing the northward dipping limb of Kalra Anticline (southeast view)

DOMELI ANTICLINE Domeli Anticline is the northernmost major

structure in the northern part of the study area

Succeeding an intraformational syncline, it represents a huge fold within the Murree Formation

The southern limb dips steeply while the northern limb is gentle. The trend of the hinge line of this fold is 40o towards northeast

DOMELI ANTICLINE

Photograph showing the northward dipping limb of Domeli Anticline. Fold axis has been eroded (northward view)

PAMAAL BACKTHRUST Pamaal backthrust coincides with the westward

plunging Kalra Anticline and has brought the Chorgali Formation above the Murree Formation in the opposite direction with respect to the major Domeli Thrust

Pamaal backthrust emplaces southward dipping beds of Chorgali Formation in contact with the northward dipping beds of Murree Formation along the Domeli Thrust

Thus, Murree Formation lies in the footwall and the Chorgali Formation occupies the hanging wall

Dip amount along this thrust is 55o to 58o towards south

PAMAAL BACKTHRUST

Photograph showing the Pamaal Backthrust (northeast view); limestone beds dipping southwards

CROSS SECTION ALONG LINE AB OF MAP

CROSS SECTION ALONG LINE CD OF MAP

CONCLUSIONS Domeli area, being located in the eastern Salt

Range has undergone severe deformation because of its association with the Salt Range Thrust in the south and Main Boundary Thrust in the north

The major trend of the structures in the study area is northeast-southwest, which indicates that the area has undergone northwest-southeast compressional deformation

Two major forethrusts (Kalra and Domeli) and a backthrust (Pamaal) are mapped in the study area

The forethrusts are southeast verging while the backthrust is northwest verging

CONCLUSIONS The major tectonic transport direction is

southeast Major anticlines of the area are Domeli

Anticline exposing Miocene age Murree Formation in its core and Kalra Anticline which lies to the south of Domeli Anticline and exposes Chorgali Formation in its core

Based on the attitude data of the limbs of Domeli Anticline, it is concluded that the fold is partially overturned and hence is asymmetrical

CONCLUSIONS The unusual greater thickness of the Murree

Formation in the northern limb of the Domeli Anticline can be attributed to a couple of blind thrusts which terminate at the level of Murree Formation in the subsurface

The intensity of thrusting is higher towards the eastern portion of the study area bringing Eocene carbonates to the surface along the Domeli Thrust, while the thrusting is comparatively less intense in the western half of the study area as Eocene rocks are not exposed there