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Day 1 in khewra gorge


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Field Report By Kashif Maqbool University of Sargodha

Day 1 in khewra gorge

  1. 1. Khewra Gorge and Chowa Road section Day 1 1 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
  2. 2. Khewra Gorge and Chowa Road section Day 1 2 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
  3. 3. Khewra Gorge and Chowa Road section Day 1 3 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)
  4. 4. Khewra Gorge and Chowa Road section Day 1 4 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.
  5. 5. Khewra Gorge and Chowa Road section Day 1 5 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.
  6. 6. Khewra Gorge and Chowa Road section Day 1 6 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.
  7. 7. Khewra Gorge and Chowa Road section Day 1 7 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.
  8. 8. Khewra Gorge and Chowa Road section Day 1 8 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.
  9. 9. Khewra Gorge and Chowa Road section Day 1 9 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.
  10. 10. Khewra Gorge and Chowa Road section Day 1 10 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.
  11. 11. Khewra Gorge and Chowa Road section Day 1 11 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.
  12. 12. Khewra Gorge and Chowa Road section Day 1 12 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.
  13. 13. Khewra Gorge and Chowa Road section Day 1 13 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.
  14. 14. Khewra Gorge and Chowa Road section Day 1 14 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
  15. 15. Khewra Gorge and Chowa Road section Day 1 15 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.
  16. 16. Khewra Gorge and Chowa Road section Day 1 16 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
  17. 17. Khewra Gorge and Chowa Road section Day 1 17 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
  18. 18. Khewra Gorge and Chowa Road section Day 1 18 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:
  19. 19. Khewra Gorge and Chowa Road section Day 1 19 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
  20. 20. Khewra Gorge and Chowa Road section Day 1 20 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
  21. 21. Khewra Gorge and Chowa Road section Day 1 21 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
  22. 22. Khewra Gorge and Chowa Road section Day 1 22 similar to casts and molds in fossil preservation. Occurring as they do only at the bottom of beds. Load Casts
  23. 23. Khewra Gorge and Chowa Road section Day 1 23 Hoddows Structures: These are Hoddows structures which are found in Salt Range Formation. Chopboard weathering: We observed chopboard weathering in Jutana Dolomite.
  24. 24. Khewra Gorge and Chowa Road section Day 1 24 Stalactite Burrows:
  25. 25. Khewra Gorge and Chowa Road section Day 1 25