CHAPTER# 1IntroductionThefollowing report provides knowledge about correlation of upper Gaj carbonatewith the help of its petrography, geochemistry and sedimentology. That are muchhelpful for predicting the depositional environment and its provenance. Ascarbonates have very much significance in different industries and is availablein vast amount in our country, so that is much important to study about it andgain benefit from this natural resource. For the following purpose the Carbonate rocksof Upper Gaj formation, Miocene age are selected for study and to constructtheir correlation in Sona Pass area and Hub Dam area.
Both the areas arecovered by rocks of Nari and Gaj formation of Oligocene and Miocenerespectively, having major lithologies are Sandstone, Limestone and shale.Physiography of AreaThefield area is a part of semi-arid to arid region at the boundary of Sindh and Baluchistannear the coast of Arabian Sea, with one major stream i.e. Hub River. As theaverage rainfall is low so mechanical weathering is dominant. Relief isgenerally moderate. In summer the temperature ranges from 30°C to 40°C and inwinter it ranges from 15°C to 25°C (mean climate of 2007 by Pakistanmetrological department).
Location of AreaThefirst area is located East of Baluchistan and West of Hub River. It is part ofSokran district. Second area which is of Sona Pass is located in the south westernside of Karachi. Structurally it is on the common flank of Cape Monze Anticlineand Lalji Syncline, in the South of Hub River.
Previous Work Geochemistryand sedimentology of Jhill limestone of Gaj formation, in Cape Monze andadjoining area, Karachi (Shahid Naseem, Shamim Ahmed Sheikh, M. Qadeeruddin); ObjectiveTostudy the chemical and petrographic properties of Jhill limestone of Gajformation, for correlation of the area, to predict depositional environment andprovenance and most importantly for the determination of its capability in thegeneration of hydrocarbon in future. CHAPTER# 2Instrumentationand MethodologyThearea of Hub Dam site and Sona Pass was selected for the sampling due to easyaccessibility, vast exposure and presence of maximum characters of theformation units. Thin Section Preparation· Start by cutting an 8-10 mm piece fromyour main stone sample by using Geoforms’s left side cutting station.
Grind theglass slide to make its surface rough to fix the stone sample onto the slide.Rub the stone sample’s flat surface with Silicone carbide water to make itssurface rough.· Fix the sample to the glass slide usingKEPT epoxy resins then the samples can be placed in the Geofix to assist inbonding the sample to the glass slide under pressure.· Using the Geoforms’s left side station,put the glass slide to the Vacuum chuck, and then cut your samples up toapprox. 2.
0 mm thickness by using the special slide cut mechanism on theGeoform.· Then place the sample to the rightstation of the Geoform, using the vacuum you can precisely grind your sample.Touch the stone with the micrometer and adjust the digital positioning of themicrometer to zero, then start grinding the stones surface with the grindingcup from approx.
2.0mm to 80 microns. You can grind with 50 mic steps when thesamples thickness is 200 micron· Set the Kemtech vacuum jig to therequired final thickness and then mount the uniformly ground samples to thevacuum jig face.· Lap on the Kemtech III machine using a Siliconcarbide/water mix until the jigs diamond faced stop ring fully contacts thecast iron lapping plate. There is a change in sound when this point is reached.This means the slides have been lapped to the set thickness.· Remove the slides from the jig and cleanand inspect.
The slides are now ready for polishing on the Kemtech III.· Clean the Vacuum jig in an ultrasoniccleaner to ensure all lapping slurry contamination has been removed and adjustthe diamond stop ring so that it is above the vacuum face plate.· Change the cast iron lapping plate tothe aluminum lift off disc and mount a PSU-M polishing pad.· Charge the Aku-Disp slurry pump(separate pump heads are available) with Diamond suspension and program thepump to dispense a 2 second supply of slurry every 8-10 seconds.
· Mount the now lapped samples to the cleanvacuum jig and polish on the PSU & MBL cloths working down the Diamondsuspension micron size to the required thickness and surface finish, approx.30micron. Remove the samples and clean. · The slides are now ready for analysis. Geochemical Analysis of the Sample:1. Loss On Ignition (LOI)· Red hot the crucibles on mason burner.
· Cool the crucibles in desiccator up toroom temperature.· Weigh crucibles and number them withpermanent glaze.· Add approximately 1gram of sample incrucibles and put them in Furness at 950oC to 1000oC forone hour.· Remove sample from Furness and placethem in desiccator until they get cool.· Weight the sample again. (Loss-on-IgnitionStandard Operating Procedure, Lac Core, National Lacustrine core facility, 2013) 2. Insoluble Residue (IR) · Take exact 1 gram sample of limestone in250ml beaker.· Add 5-10 ml of hydrochloric acid, andheat.
· Add 50ml distilled water in to thebeaker.· Now filter the solution, from filterpaper no 41 in to 250ml flask.· Take a crucible, red hot it on burner, thenput in desiccator up to room temperature and weight it.· Put the filter paper in the crucible andburn it on mason burner.· Put the crucible in desiccator up toroom temperature.
· Weight the sample and subtract thecrucible weight. 3. Neutral,Viscous, Crystal Retardant or Refractory Oxides (r2o3) · Take the filtered solution obtainedafter the IR test in flask.· Fill the distilled water up to mark. · Pipit out 100ml of solution into the250ml beaker.· Add few drops of Nitric acid (HNO3),a small piece of litmus paper, then Ammonium Chloride (NH4CL) withspatula and few drops of Ammonia.
· Heat the solution and leave for 24hours.· Filter the solution in to 250ml flask.· Take a crucible, red hot it on burner,then put in desiccator up to room temperature and weight it.· Put the filter paper in the crucible andburn it on mason burner.
· Put the crucible in desiccator up toroom temperature.· Weight the sample. 4. Titrationby Ethylenediaminetetraacetic acid disodium salt (EDTA) for Calcium (Ca)· Take the filtered solution obtainedafter the r2o3 test in flask.· Fill the distilled water up to mark.
· Pipit out 50ml of solution into the250ml beaker.· Add a pinch of Potassium Syenite (KCN)and Ascorbic acid with spatula in solution.· Add Peten & reader indicator.· Then add few drops of precipitator (i.
e.Buffer 12).· Titrate the solution by EDTA and markthe reading on burette.
5. Titrationby Ethylenediaminetetraacetic acid disodium salt (EDTA) for Magnesium (Mg)· Take the filtered solution obtainedafter the r2o3 test in flask.· Fill the distilled water up to mark. · Pipit out 50ml of solution into the250ml beaker.
· Add a pinch of Potassium Syenite (KCN)and Ascorbic acid with spatula in solution.· Add Eochrom Black T as indicator.· Then add few drops of precipitator (i.e.Buffer 10).· Titrate the solution by EDTA and markthe reading on burette. CHAPTER# 3General GeologyRegionalTectonics and Stratigraphy:Inglobal tectonic perspective, Pakistan is situated at junction of three plates,the Indian plate, Arabian plate and Eurasian plate (Kazmi and Jan 1997).
TheIndus basin is situated on north western corner of Indian plate. The Indianplate after separating form African plate during Jurassic-Early Cretaceousstarted drifting in north east direction and collided with Eurasian plate inPaleocene. The collision is characterized by continent-continent collision,obduction and thrusting is considered the prototype Alpine –Himalayan orogeny(Powell 1979). Thistectonic activity related Himalayan orogeny continued through the Oligocene toPleistocene and in between there was change in climate in clastic in shallowwater carbonates were deposited in the southern Indus Basin. Upper Indus Basinwas uplifted as a result of collision between Indian and Eurasian plate.
Nariformation is developed in these localized basins and exposed extensively in theKirther and Suleiman region and out crop scattered in the tectonised thrustblocks in the Baluchistan ophiolite and thrust belt (Blanford 1876, Williams1859). Tectonically the studyarea is the part of Karachi embankment, geographically andgeologically, Karachi embayment is situated in the southernmost part ofPakistan and Indus Basin respectively. Precisely, it is a part of southernmostcontinuation of Kirthar fold belt and south-western margin of lower IndusBasin. It is bounded by Ornachnal Fault in west and Hyderabad in east. Thesouthern part of Karachi embayment is submerged in the sea presently.
TheTrough is characterized by thick Early Cretaceous sediments and also mark thelast stages of marine sedimentation. It contains large number of narrow chainlike anticlines, some of which contain gas fields (Sari, Hundi and Kothar). TheEarly, Middle and Late Cretaceous rocks are well preserved in the area. It hasbeen a trough throughout the geological history. The Upper Cretaceous is markedby westward progadation of a marine delta. The most interesting feature ofKarachi Trough is the reportedly continued deposition across the Cretaceous /Tertiary (K/T) boundary wherein Korara Shales were deposited.
Thewestern part of Central and Southern Indus Basin was uplifted, though locallymarine conditions persisted in parts of the Karachi Trough and the presentIndus Offshore area. The Oligocene Nari Formation developed in these localizedbasins consists of high energy limestone, ferruginous sandy siltstones and somelocal shales. In the Offshore area, reefs have been recognized near theshelf-slope break. Miocene/ Pliocene sediments were deposited in the depressionareas of the Siwalik Basin which was formed as a result of the development ofthe proto-Indus drainage system. This is characterized by fluvialsedimentation.Tectonics of PakistanThe Indian Ocean and the Himalayas, two ofthe most pronounced global features surrounding the Indo-Pakistan subcontinent,have a common origin. Both are the product of the geodynamic processes ofsea-floor spreading, continental drift and collision tectonics.
A plate of theearth’s crust carrying the Indo-Pakistan landmass rifted away from thesupercontinent Gondwanaland followed by extensive seafloor spreading andopening up of the Indian Ocean. Propelled by geodynamic forces the Indian Platetravelled 5,000 km northward and eventually collided with Eurasia. Thesubduction of the northern margin of the Indian plate finally closed the Neotethysand the Indian Ocean assumed its present widespread expanse. This collisionformed the Himalayas and the adjacent mountain ranges (Kazmi and Qasimjan,1997).In the Himalayas the main uplift began inmid-Miocene time. Coincident with the Himalayan uplift, mid Miocene deformationaffected the Khojak flysch in the transform belt thus initiating transpressivesubduction along what became the Chaman Fault zone.
In the Pliocene the mostsignificant event was the collision between the Zagros portion of Arabia andEurasia (Pakistan Hydrocarbon Habitat).Tectonics of Pakistan is characterized by thetwo convergent boundaries:In the northeast there is an activecontinent-island arc continent collision boundary, the west end of the HimalayaOrigen.In the southwest, there is an active boundaryof oceanic lithosphere subducting beneath the arc trench gap, sediment andcontinental sediments, the oceanic part of the Arabian plate passing under theMakran arc-trench gap and afghan micro plate.Pakistan comprises two mainsedimentary basins, Indus Basin and Baluchistan Basin which evolved throughdifferent geological episodes and finally welded together duringCretaceous-Paleocene along Ornach Nal/Chaman Strike slip faults.The main feature thatcontrol the sedimentation of proto-Indus basin up to Jurassic was Pre-CambrianIndian Shield whose topogrpahic highs exist in the form of Kirana Hills.Following the classification of IndusBasin:Upper Indus Basin(Kohat sub-basin, Potwar sub-basin)Lower Indus Basin(Central Indus basin, Southern Indus basin)Lower Indus BasinIt is mainly comprisesof Central and Southern Indus Basin.
The Cape Monze Area is a part of Southernbasin, therefore only the Southern Indus Basin description is given below.Southern Indus basinThis basin is locatedjust south of Sukkur rift. A divide between central and southern basin itcomprises the following five main units (Qadri, 1995). 1. Thar Platform 2. Kirthar Foredeep 3. Karachi Trough 4.
Offshore Indus5. Kirthar fold belt Structure of the Area The Kirther formation is underlain by Nari andGaj Formation of Oligocene-Miocene ages respectively deposited on thenorthwestern edge of the Indian continental shelf. Structures arenortheast-southwest oriented with folds plunging mainly towards southwest. PirMangho Anticline and Lalji Syncline are the major structures of the region.
Both are fault induced folds indicated by their double hinges and kinkgeometries. Thrust is blind and not exposed in the region; however severalsinistral strike slip faults transect the areas which are antithetic to thetectonic transport of the Karachi arc.Major folding of thestrata has taken place on frontal ramps while at places oblique ramps are alsothe cause of some folding. Pir Mangho Dome is a consequence of thrusting onsuch a pair of ramps. Structural vergence indicates tectonic transport towardssoutheast. However, structures of the region may have been initially northsouth oriented and may have been rotated clockwise, evidenced by the presenceof some extensional structures to the south of the area. However, partlystructural geometry of the Karachi arc is original, evidenced by the presenceof en-echelon folds. Eastward tectonic transport of the Karachi arc is post Miocenein a thin skinned fashion as a result of India -Arabia convergence.
These structuralgeometries extend towards north and northeast all along the Karachi arc and theKirther fold belt. Stratigraphy ofLower Indus Basin General Stratigraphyof Gaj FormationThe term Gaj series was first introducedby Blanford (1876, 1878, and 1879) for sequence of shale and sandstone withsubordinate limestone (Cheema et al., 1977). Williams (1959) referredthis series as Gaj Formation which is synonymous to lower and upper Gaj(Pascoe, 1963).TheMiocene is represented by the Gaj formation and occurs in two separate areas ina narrow zone between Karachi and Quetta, generally coinciding with the easternportion of Nari distribution.Lithology:The formation consists of shale with subordinate sandstoneand limestone.
The shale is variegated greenish grey and gypsiferous. Thesandstone is brown greenish grey calcareous ferruginous and cross-bedded. Thelimestone is brown or yellowish white argillaceous and fossiliferous.Thickness: At type locality (Gaj river) it is 650 meters thick. Insubsurface, offshore Karachi it is 50-65 meters thick and 90 meters in Quetta.
Contact: Itsupper contact with Siwaliks Group and lower contact with Nari Formation istransitional and conformable. Gaj/Nari contact is exposed north of karachi.The Gaj formation has three units· Meetan Clay· Jhill Limestone· Talawa Limestone· Drig Clay Metan ClayMetanis the oldest unit of Gaj formation. The dominant lithology of Metan is shalewhich is inter bedded with thin layer of limestone. Fresh color of shale isbrownish grey and also have clay content with shale.Jhill LimestoneJhillis second unit of Gaj formation. It is composed with limestone.
Generally it isvery hard massive nodular limestone of creamy white color, with very highfossil content. Talawa Limestone Thisunit is composed with yellow color limestone which is hard and compacted and ishighly fractured. ERA PERIOD EPOCH FORMATION MEMBER LITHOLOGY CENOZOIC Quaternary Recent Alluvium Sub-Recent Alluvium Pliocene-Pleistocene Manchar Sand, Shale & Subordinate conglomerate. Tertiary Miocene Gajj Drig Clay Talawa Limestone Jhill Limestone Metan Clay CHAPTER# 4Correlation ofUpper Gaj Carbonates in Sona Pass and Hub Dam Area on the basis of theirPetrography and Geochemistry CHAPTER# 5EconomicImportanceAscarbonates are chemically precipitated rocks and contains different kinds offossils that generates the hydrocarbon through the time and can preserve thisas a fossil fuel, so they can be used as a source rock as well as a goodreservoir rock and can be beneficial for petroleum industries.
The world’slargest oil and gas fields are mostly contained in porous limestone.Most carbonate rocksare made into crushed stone and used as a construction material. It is used asa crushed stone for road base and railroad ballast. It is used as an aggregatein concrete.
It is fired in a kiln with crushed shale to make cement.Some varieties ofcarbonates perform well in these uses because they are strong, dense rocks withfew pore spaces. These properties enable them to stand up well to abrasion andfreeze. It is much easier to mine and does not exert the same level of wear onmining equipment, crushers, screens, and the beds of the vehicles thattransport it.Some additional butalso important uses of limestone include:· Dimension Stone: Limestone is often cutinto blocks and slabs of specific dimensions for use in construction and inarchitecture. It is used for facing stone, floor tiles, stair treads, windowsills, and many other purposes.
· Roofing Granules: Crushed to a fineparticle size, crushed limestone is used as a weather and heat-resistantcoating on asphalt-impregnated shingles and roofing. It is also used as a topcoat on built-up roofs. · Flux Stone: Crushed limestone is used insmelting and other metal refining processes. In the heat of smelting, limestonecombines with impurities and can be removed from the process as a slag. · Portland cement: Limestone is heated ina kiln with shale, sand, and other materials and ground to a powder that willharden after being mixed with water. · Ag Lime: Calcium carbonate is one of themost cost-effective acid-neutralizing agents. When crushed to sand-size orsmaller particles, limestone becomes an effective material for treating acidicsoils.
It is widely used on farms throughout the world. · Lime: If calcium carbonate (CaC03) isheated to high temperature in a kiln, the products will be a release of carbondioxide gas (CO2) and calcium oxide (CaO). The calcium oxide is a powerfulacid-neutralization agent. It is widely used as a soil treatment agent (fasteracting than aglime) in agriculture and as an acid-neutralization agent by thechemical industry. · Animal Feed Filler: Chickens needcalcium carbonate to produce strong egg shells, so calcium carbonate is oftenoffered to them as a dietary supplement in the form of “chickengrits.” It is also added to the feed of some dairy cattle who must replacelarge amounts of calcium lost when the animal is milked. · Mine Safety Dust: Also known as”rock dust.
” Pulverized limestone is a white powder that can besprayed onto exposed coal surfaces in an underground mine. This coatingimproves illumination and reduces the amount of coal dust that activity stirsup and releases into the air. This improves the air for breathing, and it alsoreduces the explosion hazard produced by suspended particles of flammable coaldust in the air.
· Limestone has many other uses. Powderedlimestone is used as a filler in paper, paint, rubber, and plastics. Crushedlimestone is used as a filter stone in on-site sewage disposal systems.Powdered limestone is also used as a sorbent (a substance that absorbspollutants) at many coal-burning facilities.