The Salt Range formation

The Salt Range is a hill system in the Punjab province of Pakistan, deriving its name from its extensive deposits of rock salt. The range extends from the Jhelum River to the Indus, across the northern portion of the Punjab province. The Salt Range contains the great mines of Mayo, Khewra, Warcha and Kalabagh, which yield vast supplies of salt. Coal of a medium quality is also found.

Sakaser and Tilla Jogian are the highest peaks of Salt Range. Khabikki Lake and Uchhali Lake are lakes in the Salt Range.The Salt Range forms the southern border of the hydrocarbon bearing Potwar basin in northern Pakistan, along the northwestern margin of the Indo- Pakistani plate (Sameeni,2009). The Eocene rocks exposed in the Salt Range are divided from base to top into Nammal Formation, Sakesar Formation and the Chorgali Formation respectively. The nomenclature of the Eocene succession in the Salt Range as accepted by the Stratigraphic Committee ofPakistan (Fatmi, 1973) The term “Chorgali beds” of Pascoe (1920) has been formalized as Chorgali Formation by the Stratigraphic Committee of Pakistan. The formation also represents the “Passage beds” of Pinfold (1918) in the Attock area, “Bhadrar Beds” of Gee and Evans (In Davies and Pinfold 1937) in the Salt Range and “Lora Formation” of Latif (1970a)in the Hazara area.

The Eocene rocks exposed in the Salt Range are mainly the limestones, marls, clays and shales and highly rich in well preserved fossils. The fossil pelycepod were collected from Chorgali Formation locally known as Bhadrar Beds. The present collection was carried out from the basal beds of Chorgali Formation which consists of mainly soft marl and argillaceous limestone, located about one kilometer east to south-east of the Nurpur village, Salt Range

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INTRODUCTION

The Indus Basin of Pakistan is divided into two parts i.e. Lower Indus Basin and Upper Indus Basin. The Upper Indus Basin is further divided by Sargodha high way in to two parts. Towards the east of the Sargodha highway is Potwar Plateau and towards the west is Kohat Plateau. The region of the North Punjab called as Potwar Plateau, is bound in the South by Salt range and in North by MBT as shown below.

Fig. 1. Location of the study area with reference to regional tectonic framework. The Indus River in the east Separate Kohat from the Potwar Plateau and the MBT marks its northern extremity.

The name of Salt range was first use by ELPHISTON in 1808. The name is derived from the fact that area contains huge reserve of the common table salt. Salt range is one of the few most important localities in the Sub-continent for its interesting structural, valuable stratigraphic and paleontological record. Salt range is characterized by extensive Anticlines folds, Synclines folds and various types of Faults. It is also important as a source of minerals e.g. Halite, gypsum, Coal, fire clay etc. The occurrence of these minerals is important in stratigraphic as well as paleontological point of view. That’s why Salt range sequence of Pakistan has fascinitated Geologist from all over the world due to its well preserved faunal assemblages.

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The Salt range is mainly divided into two parts. The area to the east of the river Indus “Main Salt range” or “Cis-Indus Salt range” and the area to the west of river Indus is called “Trans-Indus Salt range”. The main Salt range is further divided into three parts:

Western Salt Range Central Salt Range Eastern Salt range.

Eastern Salt range is about 16km and its height about the sea level is 760m. The western range is widens westward to the width of about 32km with highest attitude of 1422m at Sakessar. Similar central Salt range is more wider then eastern and western Salt range.

The Salt range strikes almost East-West and terminates at Kalabagh where the range is intersected by river Indus. Beyond the river Indus the ranges beaks out into various ranges collectively referred as Trans-Indus ranges. The rocks in the Salt ranges are generally folded and are typically marked by large and small scale faulting as well as local over-thrusting with movements towards south. The sedimentary sequence ranges from Pre-Cambrian to the Eocene and recent age. It is also marked by several unconformities.

In our field visit to the Salt range, we have visited only eastern and Western Salt range of the main Salt ranges. In the Eastern Salt range, we studied the Khewra Gorge, while in the western Salt range we studied the Nammal Gorge and Zaluch Nala section. We have studied the stratigraphy and detailed litology of the various formation exposed in the above said Gorges.

some of the very important mineral deposits e.g. Khewra Salt mine, Coal deposits, Iron ores etc.

STRATIGRAPHY OF THE REGION

The rocks of the Salt ranges stratigraphic units ranges in the age from Pre-Cambrian to the Tertiary with the marked absence of Ordovician , Silurian, Devonian and Carboniferous age throughout the region. Locally a given stratigraphic rock sequence pinches out laterally to the point of vanishing e.g Mesozoic sequence is well developed in the western salt range and Trans-Indus ranges but the Triassic and Jurassic and perhaps all the cretaceous formations are conspicuously absent in the most of the central and eastern Salt range.

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An igneous intrusion of the younger age is also present in the Cambrian age rock called as “Khewrite’ or “Khewra Trap”. Several types of unconformities are also present in the area which also includes paraconformity, Permotriassic unconformity and Permocambrian unconformity.

following three Gorges in the main Salt range during our field to that region:

Khewra Gorge (Eastern Salt range)

Nammal Gorge (Western Salt range)

Zaluch Nala (Western Salt range)

The description and Stratigraphy of the above three Gorges areexplained as:

AGE GROUP &FORMATIONPleistocene and late Kalabagh Conglomeratespliocene (naushahra sandstone and

conglomerates)

LITHOLOGYBrown and gray conglomerates with sandstone and clay interbeds

Major UnconformityPliocene &late Miocene

Late Miocene

MiddleMiocene

Early Miocene

SIWALIK

GROUP

Rawalpindi GROUP

SOAN

Dhok Pathan

Nagri

Chinji

Kamlial

Muree

light coloured sandstone &conglomerate light red and gray claysRed-brown clays with gray sandstone; conglomeratic near IndusGreenish -gray sandstone and clays; Conglomeratic near Indus

Bright red clays with sandstone

Massive red and brown sandstones, dark red clays

Massive sandstones, dark red and purplish clay-shales; basal conglomerate

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Major Unconformity

Early

Eocene

Paleocene

ChharatGroup

Makarwal

Group

Chor Gali(Bhadar Beds)

Sakesar

Nammal

Patala

Lockhart(Khairabad)

Hangu(dhak pass)

Olive-green shales withbedded Limestones Massive and nodular limestones, with marls; chert in upper part Light gray calcareous shales and limestone

Green shales with coal seam in east; thin limestonesGray, semi-nodular and marly limestones

Impure limestones, sandstones, and shales, often carbonaceous

Major UnconformityEarly Lumshiwalcretaceous Surghar

groupEarly Chichalicretaceous & (belemnite beds)late Jurassic

UnconformityMiddle Jurassic Samana suk

(barochBaroch limestones)Group Shinawari

EarlyJurassic

Data(variegated beds)

UnconformityLate Kingriali

Triassic (kingrialidolomite)

Musakhel TredianMiddle Group (kingrialiTriassic sandstone)

Light-colored sandstoneswith carbonaceous bands

Dark green to blackglauconitic shales and sandstones

Gray and purple bedded limestones with shale interbedsAlternating limestone, shale and siltstone;sandstone at topSandstones withlimestones, carbonaceous shales and lateritic zones

Massive light colored dolomite and dolomitic limestones, with sandstones Massive gray and purplish sandstone, with thin carbonaceous bands

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Mianwali Olive-green and gray shalesEarly (ceratite beds) with thin limestones and

Triassic sandstones

ParaconformityChhidru Limestone, marl and

(Up. Productus) calcareous sandstoneLate Zaluch Wargal Massive gray limestones;

Permian Group (Middle occasional thinProductus) carbonaceous bands

Amb Calcareous sandstone and(Lower impure limestone;Productus) carbonaceous shale

interbedsSardhai Dark purple and lavender

(Lavender clays) clays with subordinatesandstones

Early

Permian

NilawahanWarchha

(SpeckledGroup sandstones)

Dandot(conularia beds)

Tobra(talchirconglomerates)

Red and light coloredsandstones and grits in part arkosic; calys interbeds Olive-green and gray sandstones and shales, occasionally carbonaceous Conglomeratic sandstones and shales, boulders mainly igneous or metamorphic

Major Unconformity

Jhelumgroup

Middle&

Early(?) JhelumCambrian

Group

Baghanwala( saltpseudomorphbeds)

Jutana(magnesiansandstone)

Kussak(neobolus shales)

Khewra(purplesandstones)

Blood-red shales andflaggy sandstones; with salt pseudomorphs

Massive light-colored dolomite and dolomitic sandstones; subordinateshalesGray and purplish shales and glauconitic sandstones; pebble-bed at baseMassive maroon fine-textured sandstones; maroon shales and flags below

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Red gypseous marl with

Eocambrian Salt Range Formation rocksalt; gypsum-dolomite above; occasional oil shale

Central Salt Range:

CHHARAT GROUP:

NAMMAL FORMATION: This formation is the first member of the Cherat group. Cherat group

represents the Eocene strata of the Salt range. HISTORY:

“Nammal limestone and shale” by Gee (1935), “Nammal Shale” by Danilchik and Shah (1967), is named as Nammal formation by Stratigraphic committee of Pakistan. LITHOLOGY:

Main lithology of this formation is shale, marl and limestone alterations. Shale is gray to green and fossiliferrous. Lime stone is gray to bluish, argillaceous and highly fossiliferrous. Marl is light gray to bluish gray and is also fossiliferrous. ENVIRONMENT OF DEPOSITION:

Environment of deposition of this formation is shallow marine to lagoonal environment. THICKNESS:

Thickness of this formation at its type locality is 100m.

CONTACT: The upper contact of this formation is with overlying Sakessar

formation and is transitional and conformable. The lower contact of this formation is with underlying Patala formation and this contact is also conformable. FOSSILS AND AGE:

Various fossils found in this formation are Foraminifera and mollusks. Due to the presence of these fossils, age assigned to this formation is Early Eocene.

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SAKESSAR LIMESTONE: This formation is the second member of the Cherat Group.

HISTORY: “Sakessar Limestone” by Gee in 1935 was accepted by the Stratigraphic committee of Pakistan.

LITHOLOGY: Bulk of lithology of this formation is limestone which is cream to light gray in

color, nodular, and massive in the upper part and also highly fossiliferrous. Light gray colored Marl is also found in the top most part and having Chert nodules. THICKNESS:

Thickness of this formation in Salt range is from70-150m. CONTACT:

The upper contact is with Chorgali formation and this contact is transitional and conformable. The lower contact is with Nammal formation and it is also conformable. FOSSILS AND AGE:

Various fossils found in this formation are Foraminifera, Mollusks and Echinoids. Due to the presence of these fossils, the age assigned to this formation is Early Eocene.

The last member of Cherat group is missing in the Nammal gorge. So the Sakessar formation is the last formation that we have seen in the Nammal gorge.

CHORGALI FORMATION: This is the 1st member of Cherat Group.

HISTORY: “Chorgali beds” by Pascoe (1920) has been formalized as Chorgali Formation by

SCP. This formation also represents the “Passage beds” of Pinfold (1918) in the Attock area “Badhrar beds” of Gee and Evans (in Davies and Pinfold 1937) in the Salt Range and “Lora Formation” of Latif (1970a) in the Hazara area.

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LOCATION & TYPE SECTION: The section exposed in the Chorgali Pass (Lat. 33°26'30"N :

Long. 72°41'E) in the Khair-e-Murat Range, has been chosen as the type section. LITHOLOGY:

According to Cheema et al. (1977), the formation is composed of shale and limestone.

In the Khair-e-Murat Range, it is divisible into two distinct units. The lower unit comprises dolomitic limestone and shale. The upper unit is composed predominantly of shale with one thick bed of dark grey limestone and a bed of nodular argillaceous limestone near the top.

In Salt Range, the formation is also divisible into two parts. The lower part consists of shale and limestone, while the upper part is mainly limestone. DISTRIBUTION:

The formation is distributed in the eastern Salt Range, Kala Chitta Range, Khair-e-Murat Range and in the Hazara area. THICKNESS:

It is 150 m thick at Chorgali Pass, 30 m in Tarki, 15m at Bahadurkhel and about 45 m in southeastern Hazara. CONTACT:

In the Salt Range, the formation conformably overlies the Sakesar Limestone and at other places Margala Hill Limestone.

In the Salt Range, it is unconformably overlain by the Murree Formation, while conformably in other areas by the Kuldana Formation. FOSSILS:

A rich fossil assemblage including foraminifers, mollusks and ostracodes has been reported by Davies and Pinfold (1937), Eames (1952), Gill (1953) and Latif (1970c).

WESTERN SALT RANGE:

ZALUCH NALA: Zaluch Nala is located in the western Salt range. It is the type locality of the

Zaluch group rocks. In this Nala we have studied

Lei Conglomerate which are Quaternary deposits.

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LEI CONGLOMERATE: Lei conglomerates are quaternary deposits. The name “Lei Conglomerates”

was introduced by Gill in 1952 but it was earlier named as “Boulder Conglomerate” by Pilgrim in 1910. This conglomerate consists of poorly sorted pebbles and boulders of mostly Eocene rocks, with a small proportion of older sedimentary rocks, quartzites and igneous rocks. The conglomerate is intercalated with beds of soft sandstone and siltstone of pale brown to dark brown color. This conglomerate is different from the conglomerate of the Tobra formation in sense that there are no bedding planes in Lei Conglomerate but they are present in Tobra formation. Lei conglomerates are known as FANGLOMERATES because the environment of deposition of this formation is Fluvial.

Lei conglomerate

NILAWAHAN GROUP: These rocks are of Lower Permian age. It includes Tobra

formation, Dandot formation, Warcha Sand stone and Sardhai formation.

TOBRA FORMATION: This formation is the first member of the Neela Wahan group. Neela Wahan

group represent the Lower Permian strata of the Salt range. HISTORY: “Talchir boulder beds” by Gee and “Talchir stage” by Pascoe in 1959 was now named as Tobra formation by stratigraphic committee of Pakistan.

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LITHOLOGY: Main lithology of this formation is conglomerate, sandstone and shale. Conglomerate of this formation is polymictic which means that clasts of this formation are derived from various sources. Pink colored Granite clasts are very common in these conglomerates which are the part of the “Nager Parker granite” in Sindh. Metamorphic slates are also present in this formation. Striations are also present in this formation which indicates Glacio-Fluvial environment of deposition of this formation. ENVIRONMENT OF DEPOSITIION:

Environment of deposition of this formation is Glacio-Fluvial and Fluvial environment. THICKNESS:

Thickness of this formation is 20m in type locality but 133m in the western Salt range. CONTACT:

The upper contact of this formation is with Dandot formation which is transitional and conformable. The lower contact of this formation in Zaluch Nala is with Lei conglomerate which is an unconformable contact. FOSSIL AND AGE:

Various fossils reported from this formation are pollens, spores etc. Age assigned to this formation is Lower Permian.

WARCHHA SANDSTONE: This formation is the third member of the Neela Wahan

group. The second member of this group i.e. Dandot formation is missing in the Zaluch Nala. HISTORY:

“Warcha Group” by Noetling (1901) is named as Warcha Sandstone by Hussein Ahmed in 1967. LITHOLOGY:

This formation is mostly consisting of Sandstone of red to maroon color which indicates oxidizing conditions. Sandstone is medium to coarse grained and mostly thick bedded and massive. Pebbles of granite and quartzite are also present. Carbonaceous shale and coal are also present.

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ENVIRONMENT OF DEPOSITION: Environment of deposition of this formation is

non-marine, sub aerial to paludal. THICKNESS:

Thickness of this formation at its type locality is 26-80m. CONTACT:

The upper contact of this formation is with overlying Sardhai formation which is conformable. The lower contact of this formation is with underlying Dandot formation which is also transitional and conformable. FOSSIL AND AGE:

Some plants remains are found in this formation. Age aasigned to this formation is Early Permian.

SARDHAI FORMATION: This formation is the fourth and last member of the Neela

Wahan group. HISTORY:

“Upper part of the Warcha group” by Noetling (1901) is named as “Lavender Clays” or “Sardhai formation” by Gee and Pascoe in1959. LITHOLOGY:

This formation mainly consists of bluish to greenish colored clay, minor gray sandstone and gypsum and calcareous beds in the upper part. ENVIRONMENT OF DEPOSITION:

Environment of deposition of this formation is very shallow reducing marine to estuarine environment. THICKNESS:

Thickness of this formation at its type locality is 42m and in western Salt range its thickness is 65m. CONTACT:

Upper contact of this formation is with overlying Amb formation which is conformable contact. Lower contact of this formation is with Warcha Sandstone which is also conformable. FOSSIL AND AGE:

Brachiopods are commonly found in this formation. Age assigned to this formation is Early Permian.

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Sardhai Clays.

ZALUCH GROUP:

AMB FORMATION: It is the first member of Zaluch Group. Zaluch group represents

the Upper Permian strata of the Salt range. HISTORY:

“Amb sandstone beds” by Waagen (1891), “Amb formation” by Teichert is now called as Amb formation by SCP. LITHOLOGY:

This formation consists of thin to medium bedded sandstone and limestone. Thin beds of shale are also present. In some portion limestone and sandstone are mixed. When limestone is less then sandstone, then it is called as Limy sandstone. Limestone is light grey on fresh surface and grey to brown on weathered surface. Fractures are also present in limestone. Thin layers of organic shale are also present in this formation. ENVIROMENT OF DEPOSITION:

Environment of deposition of this formation is Shallow marine to palludal. THICKNESS:

This formation is well developed in the western Salt range and thin out east wards. Thickness of this formation is 80m in type locality and 47 m in Khisor range. CONTACTS:

Upper contact with Wargal limestone is conformable and the lower contact with Sardhai formation is also conformable but not present in the Nammal gorge.

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FOSSIL AND AGE: This formation is highly fossiliferrous. Typical microfossils are Forms.

Most important fossil group is foraminifera. Example of this group is fusulina which is macrofossil in this microfossil group. Brachiopods are also present. Due to presence of these fossils the age assigned to this formation is Upper Permian. Monodeoxydiacathonxis (rice like fossils) also seen here.

WARGAL LIMESTONE: It is the second member of the Zaluch group.

HISTORY: “Wargal group” by Noetling (1901), “Middle Productus limestone” by

Waagen (1879), is now called as Wargal limestone by stratigraphic committee of Pakistan. LITHOLOGY:

This formation is consists of limestone and dolomite. Limestone is argillaceous, somewhat nodular, thin to medium bedded and highly fossiliferous. Dolomite is pinkish grey in color and massive. Black colored chert nodules are also present in it. Small scale fault is also visible in this formation. ENVIRONMENT OF DEPOSITION:

Environment of deposition of this formation is shallow marine shelful, and littoral to super-0tidal environment. THICKNESS:

This formation is well distributed in the Salt range and Khisor Range. Its thickness in Zaluch Nala is 182m. CONTACT:

Lower contact with Amb formation is sharp and conformable and upper contact with Chidru formation is also transitional and conformable. FOSSILS AND AGE:

This formation is highly fossiliferous. Various fossils found are Brachiopods, Gastropods, Ammonoids, trilobites etc. Index specie Productus (brachiopod) is also found abundantly in this formation. Due to presence of these fossils age assigned to this formation is Middle Permian.

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CHHIDRU FORMAITON: This formation is third member of Zaluch group.

HISTORY: “Chidru beds” by Waagen (1891), “Chidru Group” by Dunbar

(1932) is now called as Chidru formation by the stratigraphic committee of Pakistan. LITHOLOGY:

Main lithology of this formation included limestone, sandstone, and limy sandstone. At the base of the formation, Shale unit of grey to dark grey color is also present. The upper most part has well marked Sandstone bed, which is the marker horizon and distinguishing character of this formation. ENVIRONMENT OF DEPOSITION:

Environment of deposition of this formation is shallow marine, littoral to palludal. THICKNESS:

This formation is well distributed in the western Salt ranges and Trans Indus ranges. Its average thickness at the type locality is 64m. CONTACT:

The lower contact of this formation with Wargal limestone is conformable and transitional. The upper contact with Mianwali formation is disconformable. FOSSILE AND AGE:Various fossils reported from Chidru formation are Brachiopods and ammonoites. Due to the presence of these fossils age assigned to this formation is Late Permian.

THE PERMO-TRIASSIC BOUNDARY: (The passage of Marine Permian to Marine Triassic)

The Permian rocks located in the Salt Range have richness of fauna and having relationship with the rocks of Triassic system, the strata near the Permo-Triassic boundary are marine and having conformable relationship but there is significant break in the fauna at the contact.

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Kummel and Teichert in 1966 referred to the body as Paraconformity showing sub-Arial exposure at the end of the Permian time. In support to this view, they thoroughly studied the contact throughout the Salt range to find out the lithological and textural changes across the boundary. Their work is briefly summarized as under. The upper most lithological unit of Chidru formation is sandstone bed called as white sandstone bed. The sandstone is fine to medium grained, thinly bedded with interbeds of shale while the upper contact with Kathwai member of Mianwali formation is dolomite. The Permo-Triassic boundary is marked by the following properties: There is abrupt change in the lithology at the boundary of the two system i.e. white sandstone of Upper Permian and dolomite at the base of Triassic. The upper most sandstone bed shows decrease in faunal contents which indicate change in depositional environment during the deposition of white sandstone bed. Kathwai member on the other hand also lack fossils, indicating shallow intertidal environment. The variation in thickness of white sandstone bed indicates time gap between Permian and Triassic rocks.

SALT RANGE FORMATION: It is the oldest and only Pre-Cambrian age formation exposed in the Khewra Gorge. It has three members: Sehwal marl member:

This member is further divide into two parts: It consists of dull red marl beds with some salt seems. Thick beds of Gypsum are also found. Thickness of this part is >40m. It consists of the bright red marl beds with irregular gypsum. KHEWRA TRAP is also present in this part. Thickness of this part is 3-100m.

Bandarkas Gypsum member: It is mainly massive gypsum with some salt seems. Minor beds of dolomite and clay are also present. Its thickness is >80m. Billian wala Salt member: It consists of Ferrogenous red marl with thick seems of salt. Its thickness is >650m. Conjugate fractures are present in all the members. CONTACT: Lower contact of the Salt range formation is not exposed but in some oil wells crystalline basement rocks are found. The upper contact with the

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Khewra sandstone of Jehlum group is conformable. Thickness of this formation is >830m. ENVIROMENT OF DEPOSITION: Environment of deposition is restricted basin condition with high rate of evaporation and climate is hot and arid.

Salt Range Formation.

KHEWRA TRAP: Khewra trap is highly weathered igneous body about 6m thick present

in the upper member of the Salt rage formation. It is purple to green in color. Characteristic feature is that it consists of highly decomposed radiating needles of light colored Pyroxene mineral. Its origin is crustal thinning due to normal faulting.

MUSAKHEL GROUP:

MIANWALI FORMATION: It is the first member of the Musa Khel group. Musa Khel group

represents the Triassic strata of the Salt range. HISTORY:

“Lower part of Mianwali series” by Gee (1959), “Top most limestone and dolomite beds” by Waagen (1879) was named as “Mianwali formation” by Kummel in (1969). LITHOLOGY:

This formation is mainly composed of limestone, siltstone, dolomite, shale and sandstone. This formation is divided into three members:

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Kathwai member: It is the lower most part of the Mianwali formation and

mainly consist of crystalline dolomite and interbedding of Shale. Mitti wala member:

It is the middle part of the Mianwali formation and consists of green shale beds with sandstone and limestone interbedded. Narmia member:

It is the lower most member of the Mianwali formation and mainly consists of sandy dolomite, and dark gray to brown color limestone. Sandstone interbeds are also found in this part. ENVIRONMENT OF DEPOSITION:

Environment of deposition of this formation is open marine to deltaic environment. THICKNESS:

Thickness of this formation is 127m. CONTACT:

The lower contact with Chhidru formation is marked by Paraconformity and the upper contact with overlying Tredian formation is sharp, well defined and conformable. FOSSIL AND AGE:

The various fossils found in this formation are ceratites (cephalopod), brachiopods, and conodonts. Due to the presence of these fossils the age assigned to this formation is Lower Triassic.

TREDIAN FORMATION: It is the second member of the Musa Khel group.

HISTORY: “Kingriali Sandstone” by Gee (1948), is called as “Tredian formation” by

Kummel and Gee in 1966. LITHOLOGY:

Main lithology of this formation is sandstone, which is medium to thick bedded and upper part is massive. Few beds of shale, siltstone and sandy limestone are also found. ENVIRONMENT OF DEPOSITION:

Environment of deposition of this formation is shallow marine to deltaic. THICKNESS:

The thickness of this formation in Zaluch Nala is 76m. CONTACT:

Lower contact with Mianwali formation is sharp, welldefined and conformable. The upper contact with Kingriali formation is also gradational and conformable.

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FOSSIL AND AGE: The various fossils found in this formation are plant

microfossils. Due to the presence of these fossils the age assigned to this formation is Middle Triassic.

Contact between Tredian and Kingrilai Formations

KINGRIALI FORMATION: It is the third and last member of the Musakhel group.

HISTORY: “Kingriali Dolomite” by Gee (1943) is named by Gee again in 1945 as

“Kingriali formation”.

LITHOLOGY: The bulk of lithology is dolomite, dolomitic limestone with interbeds of

dolomitic shale. The dolomite is thin to medium bedded, fine grained with inter beds of shale and marl. Cross beds are also present in this formation. ENVIRONMENT OF DEPOSITION:

Environment of deposition of this formation is shallow marine environment. THICKNESS:

The average thickness of this formation is 76-106m. CONTACT:

Lower contact of this formation is with Tredian formation and is conformable. Upper contact is with Datta formation of Jurassic age and the contact is Disconformity. FOSSIL AND AGE:

Poorly preserved Brachiopods, Bivalves, and crinoids are present in this formation. Age assigned to this formation is Early Triassic.

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SURGHAR GROUP:

DATTA FORMATION: This formation is the first member of the Surgher Group.

Surgher group represents the Jurassic and Cretaceous strata of the Salt Range. HISTORY:

“Variegated stages” by Gee (1945), “Lower part of Samana beds” by Davies (1930) is named as “Datta formation” by Danilchik in1961. LITHOLOGY:

Variegated beds of sandstone, siltstone and shale of different colors are present in this formation. Sandstone is red to maroon, grey, green and white in color. Shale, siltstone and mudstone are irregularly distributed. In the upper part thick beds of maroon shale are also present. Sulpher is mostly present in this formation indicating swamp or deltaic environment. ENVIRONMENT OF DEPOSITION:

Environment of deposition of this formation is very shallow marine to deltaic and alluvial plains. THICKNESS:

Thickness of formation at its type locality is 212m. CONTACT:

Upper contact of this formation with overlying Shinawri formation is gradational and conformable. Lower contact with underlying Kingriali formation is disconformable. FOSSIL AND AGE:

This formation is poorly fossiliferrous but some petrified wood is present there. Age assigned to this formation is Jurassic.

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SHINAWARI FORMATION: This formation is the second member of the Sur Gher group.

HISTORY: “Lowest Samana Beds” by Davies (1930), “Lower part of Kyoto

Limestone” by cutler (1933), is named as Shinawri formation by Fatmi in 1961. LITHOLOGY:

Main lithology of this formation is medium to coarse bedded limestone which is of gray to brownish gray color. It is well bedded, sandy, oolitic with nodular marl, shale and sandstone. Lime stone in the lower part has thick sandstone bed in middle and maroon shale in the upper part. ENVIRONMENT OF DEPOSITION:

Environment of deposition of this formation is shallow marine, deltaic, tidal flats and estuarine environment. THICKNESS:

Thickness of this formation at type locality is 400m. CONTACT:

Upper contact of this formation is with overlying Samana Suk formation and is transitional and conformable .Lower contact with underlying Datta formation is also Conformable. FOSSIL AND AGE:

Various fossils found in this formation are Ammonoites, Brachiopods and corals. Due to the presence of these fossils age assigned to this formation is Middle Jurassic.

SAMANA SUK FORMATION: This formation is third member of Sur Gher group. Few beds of this

formation are present in Nammal gorge but it is undifferentiated from the Shinawri formation. HISTORY:

“Bared limestone” by Gee, “Upper part of Kyoto limestone” by Cutler (1933) is named as Samana Suk formation by Davies in 1930. LITHOLOGY:

Main lithology of this formation is medium to thick bedded limestone of gray to dark gray color. This limestone is oolitic with shale beds with subordinate marl and calcareous shale. ENVIRONMENT OF DEPOSITION:

Environment of deposition this formation is shallow marine shelful to supertidal environment.

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THICKNESS: Thickness of this formation at type locality is 186m.

CONTACT: Lower contact of this formation with underlying Shinawri formation is

conformable and upper contact with overlying Chichali formation is disconformable. FOSSIL AND AGE:

Various fossils found in this formation are Brachiopods, bivalves, Gastropods and Crinoids. Due to presence of these fossils age assigned to this formation is Middle Jurassic. The rest of the three members of Sur Gher group i.e. Chichali formation, Lumshiwal formation and Kawagarh formation are absent in along a major unconformity Named as K.T Boundary.

K.T BOUNDARY: (Cretaceous-Tertiary Boundary)

At the end of the Mesozoic era and before the beginning of the Cenozoic era, there was a major Disconformity in geologic history. If we study the rocks of the Paleocene age, we find a total displacement of almost all the life on earth. The dinosaurs, plants, invertebrates etc. all are disappeared. This major Disconformity is seen all over the world. It is represented in Pakistan in the form of the laterite bed at the bottom of the Hangu formations as we go from Kawagarh formation within Hangu formation. In the lower Indus basin, it is represented between the Moro group and Ranikot group.

Scientists all over the world have presented their ideas on this matter out of which three are well known. Meteorite impact theory:

According to this a meteorite stuck the earth near the Gulf of Mexico. As a result a huge cloud rose which block the sun rays from reaching the earth’s surface. As a result all living creatures died due to their dependence on sunlight as a primary source of energy. Volcanic activity:

According to this theory, during this period repeated volcanic activity cause the formation of the huge dust clouds. Eventually blocking sunlight and other sources, thus causing the death of the living creatures on the earth.

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Change in the earth’s Magnetic field: According to this theory, the sudden reversal of the earth’s magnetism

distributed the living systems, which could not adjust to the new magnetic field and thus resulted in the death of all the living organisms. After this event some of the organisms survived. Thus these organisms are seen nowadays having different structural features as compared to these before this event.

MAKARWAL GROUP:

HANGU FORMATION: This formation is the first member of the Makarwal group. Makarwal

group represents the Paleocene strata of the Salt range. HISTORY:

The “Hangu Shale” and “Hangu Sandstone” by Davies (1930) have been formalized by the stratigraphic committee of Pakistan as Hangu formation.

LITHOLOGY: This formation consists of dark grey, rarely variegated sandstone,

shale, carbonaceous shale, and some nodular argillaceous limestone. The sandstone is white, light gray, and reddish brown, weathers dark rusty brown, fine to coarse grained and medium to thick bedded. THICKNESS:

In the Salt range area this formation is 40 to 45m thick. CONTACT:

The upper contact of this formation is with Lockhart formation and this contact is transitional and conformable. The upper contact of this formation is with Samana Suk formation and this contact is unconformable. FOSSILS AND AGE:

The various fossils found in this formation are foraminifera with some corals, gastropods and bivalves. Due to the presence of these fossils, the age assigned to this formation is Paleocene.

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LOCKHART FORMATION: This formation is the second member of the Makarwal Group.

HISTORY: Davis (1930) introduced the term Lockhart Limestone for a paleocene

limestone unit in the kohat area. LITHOLOGY:

Grey to dark gray, medium to thick massive bedded, brecciated limestone. The limestone displays very well developed nodularity. The nodularity may be caused by any of the following four reasons.

Organic activity Differential compaction Pressure solution Stretching

ENVIRONMENT OF DEPOSITION: The environment of deposition is shallow marine shelf

conditions where calcite is precipated in warm water to form limestone. THICKNESS:

In the Samana Range the formation is 60 meter thick. CONTACT:

The upper contact with Patala formation is transitional and conformable. The lower contact is with Hangu formation and the contact is also conformable. FOSSILS AND AGE:

The limestone contains abundant foraminifers, corals, mollucs, Echinoids and algea. On the basis of these fossils the age of the formation is assigned as Middle Paleocene.

PATALA FORMATION: This formation is the third member of Makarwal group.

HISTORY: Davies Pinfold (1937) named it as Patala shale which later was renamed

as the Patala Formation by the SCP. LITHOLOGY:

Alternate beds of Shale, Clay and limestone. Thin bedded sandstone and some interbedded marl and conglomerate are also present. ENVIRONMENT OF DEPOSITION:

The environment of deposition is transitional, continental and deltaic marine environment. THICKNESS:

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Type locality is in Patala nala located in the salt range area, where the thickness of the formation is 90 meters. CONTACTS:

The upper contact with overlying Nammal formation is transitional and conformable. The lower contact is with Lockhart formation and it is also transitional and conformable.

FOSSILS AND AGE: The formation is richly fossiliferrous and

contains abundant foraminifera and mollusks. On the basis of the above mentioned fauna, the age assigned to this formation is Late Paleocene.