Salt range and kohat potwar basin

1.  Salt range and kohat potwar basin:

2. Geology of salt range:
 · Salt range formation
 · Khewra Sandston
 · Kussak formation
 · Jutana Dolomite
 · Baghanwala formation
 · Nammal formation
 · Dandot formation
 · Tobra formation
 · Sakessar Limestone
 · Patala formation
 · Hangu formation
 · Warcha Sandstone

5. SALT RANGE FORMATION:
 Age: The age of Salt Range formation is early Cambrian and late
Precambrian and is inactive tectonically.
 Name: Salt Range formation
 Type locality: Khewra gorge eastern salt range Punjab has been
designated as the type section.
1. Sahwal Marl Member: It composed of gypseferrous,
igneous body called “Khewrite” or “Khewra Trap” pyroxene and oily shale.

6. 2. Bhandar Kas Gypsum:
 The member is composed of massive gypsum with minor beds of
dolomite and clay.
3. Billianwala Salt Member:
 Dull red marl beds with some salt seem and thick gypsum bed on top.
Bright red marl with irregular gypsum, dolomite beds and Khewra trap.
 In Billianwala Salt member, there we observed a cavity which has water
dissolved salt. This water dissolved salt was dropping from ceiling to
lower part. The upper water dissolved is called Stillic Tite and the lower is
called Stillic mite .Also this salt is evaporating towards ceiling.

7. Reported Lithology:
 The upper part of the salt range formation is composed of
gypsum beds, dolomite, clay, greenish & low grade oil shale;
‘Khewra trap or khewrite’ (6m thick) consisting of decomposed
radiating needle of light colored mineral, probably pyroxene.
 The lower part of the formation consisting of Marl, red gypseous
with salt consisting of thick seams.
 There are three members of Salt range formation
 Fossil: Salt Range formation contains tertiary microfossils.
 Contacts: Upper contact with Khewra sandstone normal and
conformable.

8. KHEWRA SANDATONE:
 Age: Early Cambrian.
 Name: Khewra Sandstone.
 Type Locality: The type locality of the Khewra Sandstone is in Khewra
Gorge near Khewra Town, Salt Range.
 Lithology: The formation predominantly consist of purple brown,
yellowish brown fine grained sandstone and the lower most part of the
formation consists of flaggy shale thick to massive bedded ripple marks
and mud cracks.
 Fossil: It contains Trace fossils and Trilobite trails.

9. KUSSAK FORMATION:
 Age: Mid Cambrian and early Cambrian or late early Cambrian.
 Name: Kussak formation
 Type Locality: The type locality of the formation lies near the Kussak Fort
in the eastern part of the Salt Range.
 Reported Lithology : The formation is composed of greenish grey,
glauconitic and micaceous sandstone and siltstone interbedded with light
grey dolomite and some oolitic arenaceous dolomite; with layer of
intraformational conglomerates; pink gypsum lenses at top and 5.25cm
long thin lenses of fossil asphalt (gilsonite).

10. JUTANA DOLOMITE:
 Age: Jutana dolomite is of early mid Cambrian and late early
Cambrian.
 Name: Jutan Dolomite
 Type Locality: The type locality of the formation lies neat the Jutana
village in the eastern Salt Range Punjab.
 Reported Lithology: The upper part of the formation consist of light
green to dirty white dolomite, massive; brecceated in upper part with
matrix and fragments of same rocks. The lower part consist of dolomite
of light green color, hard massive and partly sandy. The formation has
upper contact with Baghanwala formation which is conformable and the
lower contact with Kussak formation also conformable.
 Fossils: Lingulella fuchsia, botsfordia granulate, redilchia noetlingi.

11. BAGHANWALA FORMATION:
 Age:
 Mid Cambrian
 Name:
 Baghanwala formation.
 Type Locality:
 The type section of the Baghanwala formation is located near the
Baghanwala village in the eastern Salt Range.
 Reported Lithology:
 The formation is composed of red shale and clay alternating with flaggy
sandstone of several color pink, grey or blue green especially in the lower
half part. Ripple marks and mud cracks are common. Numerous
pseudomorph cast of salt crystal are present along the bedding plane
which are the diagnostic features of this formation.

12. NAMMAL FORMATION:
 Age: Early Eocene
 Name: Nammal formation
 Type Locality: The Nammal formation is exposed in the Nammal
Gorge.
 Reported Lithology:The formation comprises shale, marl and limestone
and their alternation. The shale is grey to olive green fossiliferous. The
Limestone and Marl is light grey to bluish and argillaceous at places.
 Fossils: It contains forams and mollusks.

13. DANDOT FORMATION:
 Age: Dandot formation is of early Permian age.
 Name: Dandot formation
 Type Locality: The type locality of the formation is neat Dandot
village, eastern Salt Range.
 Reported Lithology: The formation consists of light grey to olive
green, yellowish sandstone with occasional thin pebbly and
subordinate dark grey and splintery shale, fossiliferous in the basal
part. The maximum thickness is about 50m.
 Fossils: Dandot formation contains discina, martiniopsois, chonetes,
eurydesma, conalaria.

14. TOBRA FORMATION:
 Age: Tobra formation is of early Permian age.
 Name: Tobra formation
 Type Locality: The formation is located near Tobra village in eastern
Salt Range.
 The foramation comprises on three facies

15. Freshwater facies:
Freshwater facies with few or no boulders. It is an alternating facies of siltstone
and shale containing spore flora. This facies is the characteristic of the eastern Salt
Range
Complex facies:
A complex facies of diamictite, sandstone and boulder bed, the unit increase in
thickness in western Salt Range and Khisor Range.
Reported Lithology:
Tobra formation is true tillitic; the rock unit is composed of boulders of granite
withfragments of Quartz, feldspar, magnetite, garnet, claystone, siltstone,
quartzite, bituminous shale, diabase and gneiss. Some boulders are polished and
scratched. According to Teichert (1967), siltstone and shale.
Fossils:
Contains Pollens and spores.

16. SAKESSAR LIMESTONE:
 Age: Early Eocene
 Name: Sakessar Limestone
 Type Locality: Sakessar Peak in the Salt Range has been designated as
the type locality.
 Reported Lithology: The formation consists of predominantly
limestone and matrl. The Limestone is cream to light grey in color
nodular, massive and having chert in the upper part. The Marl is creamed
colored to light grey .
 Fossils: forams, mollusks and echinoids.

17. PATALA FORMATION:
 Age: Patala formation have late Paleocene age.
 Name: Patala formation
 Type Locality: The formation is exposed in Patala Nala in Salt Range
Punjab.
 Reported Lithology: The formation consists of shale and marl with
subordinate limestone and sandstone, with coal seams locally. In Salt
Range the shale is dark greenish grey.
 Fossils: Patala formation contains forams, mollusks and ostracodes.

18. HANGU FORMATION:
 Age: Early Paleocene.
 Name: Hangu formation
 Type Locality: A section south of Fort Lockhart (lat. 33 40ʺ N: long, 71
03ʹ E) has been designated as the type section and Dhak Pass (lat. 32 40ʹ
N: long. 71 44ʹ E) in the Salt Range as the principal reference section of
the formation.
 Reported Lithology: The formation consists of sandstone with grey
shale intercalation in upper part in Kohat area. The sandstone is white,
light grey and reddish brown, weathers dark brown, fine to coarse
grained, in places conglomeratic and medium to thick bedded.
Fossils: It contains forams, corais, gastropods and bivalves

19. WARCHA SANDSTONE:
 Age: Early Permian. (Assumed)
 Name: Warcha sandstone
 Type Locality: The type locality of the formation is in the Warcha
Gorge in the Salt Range.
 Lithology: Red and light colored Dominant sandstone clays
interbedded.

20.  Kohat potwar fold and thrust belt:

22. Kohat potwar fold and thrust belt:
 Introduction:
 It is also called upper indus basin.
 The Indo-Eurasian collision affected more intensively the western region
of the collision plate compared to the eastern region due to uneven
convex curve structure.
 The Kohat-Potwar plateau on the southern part of the Himalayan and
Karakorum orogenic belt is a result of compressional tectonics after the
Indo-Eurasian collision.
 The Kohat- Potwar plateau is bounded to the north by the Kalachitta
Hills. The Salt Range and Trans-Indus Range mark the boundary to the
south. The western boundary is marked by the Kurram-Parachinar
Range. The River Indus separates the Kohat-Potwar Plateau into the
Potwar area on the east and the Kohat area on the west.

23.  The Kohat Plateau is located between latitude 32N and 34N and
longitude 70E and 74E (Fig. 1).
The geological map of Kohat Plateau has been published by the
United States Geological Survey (Meissner, et. al. 1974, 1975). Tight east-
west striking anticlines are cored by steep reverse faults with broad
synclinal valleys separating them (Sercombe, et.al. 1998)

26. Stratigraphy:
 The sedimentary deposits found in the area are from Pre-Cambrian to
Recent. The deposition was interrupted several times. The two identified
unconformities are Cambrian- Permian and Eocene-Miocene in the area.
The Late Jurassic- Early Cretaceous, Cretaceous-Paleocene and Eocene-
Miocene unconformities are also marked.
 Miocene-Eocene Unconformity:
 Non-orogenic movements mainly caused by various cycles of uplift
affected pre-Eocene deposition. During the late Eocene, the area
emerged out completely while the seawater withdrew from the area

27.  Cretaceous-Paleocene Unconformity:
In the Cretaceous, the area emerged out of the sea and erosion followed
(Fig. 8). The emergence was more intense south and east of the area, as
witnessed by the absence of the Cretaceous section (Khan, et.al. 1986).
Jurassic-Cretaceous Unconformity:
The area emerged out of the sea in the Late Jurassic and
sedimentation started again in the Cretaceous, resulting in an
unconformity The subsurface stratigraphic sequence in the Kohat
Plateau cannot be demonstrated as the area is not fully exposed and the
data available is insufficient.
The thickness of Paleocene-Eocene rocks varies
dramatically from East to West (Sercombe et.al. 1998).

29. Exploration History:
 Amoco Pakistan Exploration Company (APEC) drilled three wells between
1990 and 1993 in the Kohat plateau: Tolanj-1, Kahi-1 and Sumari-1. The
Tolanj-1 well revealed a complex flower type structure, which indicates
that it is not a thrustrelated structure or an evaporite cored anticlinorium
and salt was not encountered in the well (Sercombe et.al. 1998).
 Several other companies have also explored the Kohat Plateau area in
different times, including,
 Amoco Pakistan Exploration Company (APEC).
 Pakistan Oilfields Limited (POL), Oil and Gas Development Limited
(OGDCL).
 Pakistan Petroleum Limited (PPL).
 MOL. In 2002, MOL(Tal Block) encountered gas in the Kohat area.

30. Hydrocarbon Potential:
 The Indus basin, including the Kohat-Potwar depression, belongs to the
category of extra-continental downward basins which account for 48% of
the world’s known petroleum resources (Riva, 1983).
 The Kohat-Potwar depression has several features that make it a
favourable site for hydrocarbon accumulations. Located on a continental
margin, the depression is filled with thick deposits of sedimentary rocks,
including potential source reservoir and cap rock. It contains a thick
overburden (about 3000 m) of fluvial sediments, which provide the burial
depth and optimum geothermal gradient for seeps found in this area
(Khan, et.al. 1986).
 Secondary traps may also be present within major thrust sheets,
particularly at the leading edge of the thrust sheet and above footwall
ramps (Mitra, 1990).

31. Source Rock:
 The upper most formation of Paleocene age in the Kohat- Potwar
depression is the Patala Formation.
 This formation is of extreme importance as it is considered to be the
main source rock for oil and gas produced in the basin.
 The northern part of Potwar has been proven to be the main producing
region for oil and gas in the area while the Kohat area, due to its
structural trend and tectonic pattern, has potential for hydrocarbons.