Day 1 in khewra gorge

Khewra Gorge and Chowa Road section Day 1

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Stratigraphic Sequence in Salt Range

Age Group Formation

Pleistocene Kalabagh Cong Mansehra S/St.

Conglomerate.

Pliocene, Late Miocene Siwalik Group Soan Formation

Dhok Pathan Formation

Nagri Formation

Chingi Formation

Early Miocene Rawalpindi Group Kamlial Formation

Murree Formation

MAJOR UNCONFORMITY

Early Eocene Charrat Group Chor Gali Formation

Sakesar Limestone

Nammal Formation

Makarwal Group Patala Formation

Lockhart Formation(Khanabad)

Hungu (Dhak Pass)

MAJOR UNCONFORMITY

Early Cretaceous (Early

Cretaceous and Late

Jurassic)

Surghar Group Lumshiwal Formation

Chichali Formation


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UNCONFORMITY

Middle Jurassic

Baroch Group

Samanasuk(Baroch Limestone)

Shinawari Formation

Datta Formation (Variegated

beds)

UNCONFORMITY

Late Triassic Musakhel Group Kingrali (Kingrali Dolomite)

Tradian Formation

Mianwali Formation

PARACONFORMITY

Late Permian Zaluch Group Chiddru Formation (Upper

Productus)

Wargal Limestone (Middle

Productus)

Amb Formation (Lower

Productus)

Early Permian Nilawahan Group Sardhai Formation

Warchha Formation

Dondot Formation

Tobra Formation

Major UNCONFORMITY


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On day one, we went to the Khewra Gorge located in Eastern Salt Range. We observed different

formations. They are explained below

Salt Range Formation:

Synonym: Wynne (1878) named and described the formation as ‘Saline Series’. Gee (1945)

called the same unit as ‘Punjab Saline Series’. The present name, the Salt Range Formation has

been given by Asrarullah (1967).

Type Locality: Punjab, Khewra Gorge in the eastern Salt Range has been designated as its

type locality.

Age:The age of Salt Range Formation is late Precambrian or early Cambrian.

Lithology: The lower part of the Salt Range Formation is composed ofred-coloured gypseous

marl with thick seems of salt while the beds ofgypsum, dolomite, greenish clay and low grade

Middle and Early

Cambrian

Jehlum Group Baghanwala Formation (Salt

Pseudomorph Beds)

Jutana Formation (Magnesium

Sandstone)

Kussak Formation (Glauconitic

Sandstone)

Khewra Sandstone (Purple

Sandstone)

Pre Cambrian

Salt Range Formation (Saline

Series)


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oil shale are the constituents of the upper part. A highly weathered igneous body knownas

“Khewra Trap” has been reported from the upper part of the formation. It consists of highly

decomposed radiating needles of a light-coloured mineral, probably pyroxene. The red-

coloured marl consists chiefly of clay, gypsum and dolomite with occasional grains and crystals

of quartz of variable size. Thick-bedded salt shows various shades of pink colour and well-

developed laminations and colour bandings upto a metre thick. The gypsum is white to grey in

colour. It is about 45m thick, massive and is associated with bluish grey, clayey gypsum. The

dolomite is usually light grey in colour and flaggy.

It has three members:

1. Sahwal Marl Member.

2. Bhandar Kas Gypsum Member.

3. Billianwala Salt Member.

Fossils:It is devoid of fossils.

Contacts:Its upper contact is with Khewra Sandstone which is normal and conformable and

lower contact with metamorphic rocks of Precambrian age.


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Fig .1 Gypsum beds of Salt Range Formation in Khewra gorge.

2. Khewra Sandstone:

Synonym: The name was originally proposed by Noetling (1894) as ‘Khewra Group’. Prior to

that Wynne (1878) called the formation “Purple Sandstone Series” and this name was

continued until recently when the name of the formation was formalized as “Khewra

Sandstone” by the Stratigraphic Committee of Pakistan.

Type Locality: The type locality is in Khewra Gorge near Khewra Town, Salt Range.

Age: The age of Khewra Sandstone is early Cambrian.

Lithology: The formation consists predominantly of purple to brown and yellowish brown

fine-grained sandstone. The lowermost part of the formation is red flaggy shale. The sandstone

is mostly thick bedded to massive. The Khewra Sandstone is widely distributed throughout the

Salt Range.


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Fossils:The formation contains only a few trace fossils in the Salt Range which have been

interpreted as trilobites.

Contacts:Upper contact is with Kussak Formation which is gradational and lower contact with

Salt Range Formation.

Fig 2.Purple sandstone with honey comb weathering in Khewra Sandstone.

3.Kussak Formation:

Synonym: Wynne (1878) applied the name ‘Obulus beds’ or ‘Siphonotreta beds’ to a

predominantly greenish grey, glauconitic, micaceous sandstone and siltstone. Waagen (1895)

used the name ‘Neobolus beds’ for the same unit. Noetling (1894) proposed the name ‘Kussak

Group’ and finally the Stratigraphic Committee of Pakistan named the Formation as “Kussak

Formation”.

Type Locality: The type locality lies near the Kussak Fort in the eastern part of the Salt Range.

Age:The age of the formation is either late early or early middle Cambrian.


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Lithology:The formation is composed of greenish-grey, gluconitic, micaceous sandstone,

greenish-grey siltstone, interbedded with light grey dolomite and some oolitic, arenaceous

dolomite. Numerous layers of intraformatinal conglomerate are present. Pink gypsum lenses

are present near the top. The general lithology throughout the formation is uniform. However,

thickness vary at different places.

Fossils:The formation is fossiliferous and has yielded the following fauna: Neoboluswarthi,

Bolsfordla granulate, Lingulellawanniecki, Redlichtanoetlingi.

Contacts: Upper contact is with Jutana Formation which is conformable and lower contact

with Khewra Sandstone which is gradational.

Fig 3. Shale and micaceous silt stone of Kussak Formation.


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4. Jutana Formation

Synonym: Fleming (1853) named this unit “Magnesian sandstone”. Noetling (1894) described

it as ‘Jutana Stage’. The Stratigraphic Committee of Pakistan formalized the name as “Jutana

Formation”.

Type Locality: The type locality lies near Jutana Village in the eastern Salt Range.

Age: It is early middle Cambrian or late early Cambrian.

Lithology:At the type locality the lower part of the formation consists of light green, hard

massive, partly sandy dolomite and the upper part is composed of light green to dirty white

massive dolomite. In the upper part, brecciated dolomite is also present with matrix and

fragments consisting of same rock.

Fossils:It contains Lingulellafushi, Botsfordia granulate, Redilchianoetlingi,

Pseudothecasubrugosa.

Contact:The formation is conformably underlain by the Kussak Formation and conformably

overlain by the Baghanwala Formation.

Fig 4.Massive dolomite of Jutana Formation.


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5. Baghanwala Formation:

Synonym: The name Baghanwala Formation is now given to the rocks of the ‘Pseudomorph

Salt Crystal Zone’ of the Wynne (1878) and the ‘Baghanwala Group’ of Noetling (1894). Holland

(1926) called these beds “Salt Pseudomorph be ds” and Pascoe (1959) named them

“Baghanwala Stage”.

Type Locality:It is near Baghanwala Village in the Eastern Salt Range.

Age: Early middle Cambrian

Lithology: The formation is composed of red shale and clay, alternating with flaggy sandstone.

The flaggy sandstone exhibits several colours including pink grey or blue green, especially in the

lower half of the formation.

Fossils:Devoid of fossils.

Contact:The contact of the Baghanwala Formation with the overlying Tobra Formation is

unconformable, whereas the lower contact with the Jutana Formation is conformable.


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Fig 5.Flaggy sandstone beds and shales in Baghanwala Formation.

6. Tobra Formation:

Synonym: It was previously known in the literature as “Talchir Boulder Bed” or “Talchir Stage”

of Gee and “Salt Range Boulder Bed” of Teichert (1967).

Type Locality:The type locality is located near Tobra Village in the eastern Salt Range.

Age: Early Permian

Lithology:The Tobra Formation depicts a very mixed lithology in which the following three

facies are recognized

1. Tilliticfacies exposed in the eastern Salt Range. This rock unit grades into marine

sandstone containing Eurydesma and Conularia fauna

2. Freshwater facies with few or no boulders. It is an alternating facies of siltstone and

shale containing spore flora.

3. A complex facies of diamictite, sandstone and boulder bed.

In the eastern Salt Range the Tobra Formation exhibits true trillite; the rock unit is composed of

boulders of granite with fragments of quartz, feldspar, magnetite, garnet, clay stone, siltstone,

quartzite, bituminous shale and gneiss. The matrix of the conglomerate bed is generally clayey,

sandy and at some places calcareous.

Fossils:Pollens and spores, Punctatisporites, Leiotriletes, Protohaploxypinus, and

Striatopodocarpites.

Contact:Upper contact with Dandot Formation which is gradational lower contact with

Cambrian rocks(Baghanwala Sandstone) which is disconformable.


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Fig 7.Tilaticfaciesof Tobra Formation.

7. Dandot Formation:

Synonym: The name Dandot Formation is formalized after the ‘Dandot Group’ of Noetling

(1901) and includes the “Olive Series”, ‘ Eurydesma beds’ of Wynne (1878) and the ‘Speckled

sandstone’ of Waagen (1879).

Type Locality: The type locality is near Dandot Village, eastern Salt Range.

Age:Early Permian.

Lithology:The lithology at the type locality consists of light grey to olive green yellowish

sandstone with occasional thin pebbly beds and subordinate dark grey and greenish splintery

shale.

Fossils: The Dandot Formation is fossiliferrous and the basal part in the eastern Salt Range has

yielded brachiopods including Discina species, Martiniopsis species and Chonetes species.

Contact:The formation has a gradational contact with the underlying Tobra Formation and is

terminated in sharp but conformable contact with the overlying Warchha Sandstone.


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Fig 8.shales and pebbly beds of sandstone in Dandot Formation.

8. Patala Formation:

Synonym: The term Patala Formation was formalized by the Stratigraphic Committee of

Pakistan for the “Patala Shale” of Davies and Pinfold (1937) and its usage was extended to other

parts of the Kohat-Potwar and Hazara areas.

Type Locality: The section is exposed in Patala Nala in the Salt Range.

Age:Late Paleocene

Lithology:The Formation consists of shale and marl with subordinate limestone and

sandstone. The shale is dark greenish grey, selenite bearing, in place carbonaceous and

calcareous, and also contains marcasite nodules. The limestone is white to light grey with

nodules. It occurs as interbeds. Subordinate interbeds of yellowish brown and calcareous

sandstone are present in the upper part. Coal seams of economic value are present locally.


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Fossils:Forams, molluses and ostracodes. Actinosiphontibetica, Assilinadandotica,

Discicyclineranikotensis, Lockhartiaconditi, Nummulitesgloblus, Globigerina linaperta.

Contact:Upper contact conformable and transitional with Namal Formation and lower contact

conformable with Lockhart Limestone.

Fig 9.Shale , and fire clays of Patala Formation.

9. Namal Formation:

Synonym: The term Nammal Formation has been formally accepted by the Stratigraphic

Committee of Pakistan for the “Nammal Limestone and Shale” of Gee (in Fermor, 1935) and

“Nammal Marl” of Danilehik and Shah (1967) occurring in the Salt and Trans Indus Ranges.

Type Locality: The section is exposed in the Nammal Gorge (lat. 32˚ 40˚ N :lon. 71˚ 07’ E) is

the type section.

Age:Early Eocene.


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Lithology: The formation, throughout its extent, comprises of shale, marl and limestone. In

the Salt Range, these rocks occur as alternations. The shale is grey to olive green, while the

limestone and marl are light grey to bluish grey. The limestone is argillaceous in places.

Fossils:Forams and moluscs, Assilinagranulosa, Discocyclinaranikotensis etc.

Contact:Upper contact transitional with sakeser limestone and lower contact with Patala

Formation which is transitional.

Fig 10.Nodular Limestone of Nammal Formation.

10. Sakesar Limestone:

Synonym:The term Sakesar Limestone was introduced by Gee for the most prominent Eocene

limestone unit in the Salt Range and Trasns-Indus Ranges.

Type Locality: Sakesar Peak in the Salt Range has been designated as the type locality.

Age: Early Eocene


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Lithology:The unit consists dominantly of limestone with subordinate marl. The limestone,

throughout its extent, is cream coloured to light grey, nodular, usually massive, with

considerable of chert in the upper part. The marl is cream coloured to light grey and forms a

persistent horizon near the top.

Fossils: Foramsmolluscs and echinoids, Assillinalaymeriei, Flosculineglobosa, Lockhartiaconditi

etc.

Contact:Upper contact conformable with Chorgali Formation and lower contact with Namal

Formation which is transitional.

Fig 11. Cherty nodules in massive limestone of Sakaser Limestone.


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Sedimentary Structures Observed in Eastern Salt Range:

Ripple Marks:

Ripple cross-laminae forms when deposition takes place during migration of current or

wave ripples. A series of cross-laminae are produced by superimposing migrating ripples.

The ripples form lateral to one another, such that the crests of vertically succeeding laminae

are out of phase and appear to be advancing upslope. This process results in cross-bedded

units that have the general appearance of waves in outcrop sections cut normal to the wave

crests. In sections with other orientations, the laminae may appear horizontal or trough-

shaped, depending upon the orientation and the shape of the ripples. Ripple cross-laminae

will always have a steeper dip downstream, and will always be perpendicular to paleoflow

meaning the orientation of the ripples will be in a direction that is ninety degrees to the

direction that current if flowing. Scientists suggest current drag, or the slowing of current

velocity, during deposition is believed to be responsible for ripple cross-laminae. In the field

we identify ripple marks in Khewra Sandstone.

Ripple Marks


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Cross Bedding:

In geology, the sedimentary structures known as cross-bedding refer to (near-) horizontal units

that are internally composed of inclined layers. This is a case in geology in which the original

depositional layering is tilted, and the tilting is not a result of post-depositional deformation.

Cross-beds or "sets" are the groups of inclined layers, and the inclined layers are known as cross

strata.

Cross bedding forms during deposition on the inclined surfaces of bedforms such as ripples and

dunes, and indicates that the depositional environment contained a flowing medium (typically

water or wind). Examples of these bedforms are ripples, dunes, anti-dunes, sand waves,

hummocks, bars, and delta slopes. In the field we observed cross bedding in Khewra Sandstone.

Cross Bedding


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Mud Cracks:

Mud cracks (also known as desiccation cracks or mud cracks) are sedimentary structures formed

as muddy sediment dries and contracts. Naturally forming mud cracks start as wet, muddy

sediments desiccates, causing contraction. A strain is developed because the top layer tries to

shrink while the material below stays the same size. When this strain becomes large enough,

channel cracks form in the desiccated surface material, relieving the strain. Individual cracks

spread and join up forming a polygonal, interconnected network. These cracks may later be filled

with sediment and form casts on the base of the overlying bed.

Mud Cracks

Honey Comb Weathering:


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Honeycomb weathering, also known as fretting, cavernous weathering, alveoli/alveolar

weathering, stone lattice, stone lace is a type of salt weathering common on coastal and semi-arid

granites, sandstones and limestone. Honeycomb weathering is not limited to natural settings and

can be seen to develop on buildings where a rate of development can be established. This rate

can be as fast as several centimeters in 100 years.

Cause

For honeycomb weathering to occur, a source of salt is needed because the basic mechanism for

this kind of weathering is salt heaving. Salt is deposited on the surface of the rock by saltwater

spray or by wind. Moisture must be present to allow for the salt to settle on the rocks so that as

the salt solution evaporates the salt begins to crystallize within the pore-spaces of the rock.

Porous rock is also needed so that there are pore-spaces for the salt to crystallize within. These

salt crystals pry apart the mineral grains, leaving them vulnerable to other forms of weathering. It

takes prolonged periods for this weathering to become visible, as the rock goes through cycles of

wetting and drying. We observed the honey comb weathering in Khewra Sandstone.

Honey comb Weathering


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Convolute Bedding:

Convolute bedding forms when complex folding and crumpling of beds or laminations occur.

This type of deformation is found in fine or silty sands, and is usually confined to one rock layer.

Convolutelaminations are found in flood plain, delta, point-bar, and intertidal-flat deposits.

They generally range in size from 3 to 25 cm, but there have been larger formations recorded as

several meters thick. We also observed it in Khewra sandstone.

Convolute Bedding


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Pseudomorph Salt Crystals:

In mineralogy, a pseudomorph is a mineral or mineral compound that appears in an atypical

form (crystal system), resulting from a substitution process in which the appearance and

dimensions remain constant, but the original mineral is replaced by another. The name literally

means "false form". We observed it in Baghanwala Formation.

Pseudomorph Salt Crytals

Load Casts:

Load casts or Sole marks are sedimentary structures found on the bases of certain strata that

indicate small-scale (usually on the order of centimeters) grooves or irregularities. This usually

occurs at the interface of two differing lithologies and/or grain sizes. They are commonly

preserved as casts of these indents on the bottom of the overlying bed (like flute casts). This is


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similar to casts and molds in fossil preservation. Occurring as they do only at the bottom of

beds.

Load Casts


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Hoddows Structures:

These are Hoddows structures which are found in Salt Range Formation.

Chopboard weathering:

We observed chopboard weathering in Jutana Dolomite.


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Stalactite

Burrows:


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Day 1 in khewra gorge

Science

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