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Title of Thesis

Ghulam Abbas
Institute/University/Department Details
Institute of Geology/ University of the Punjab
No. Date
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
microfacies, kirthar formation, ghazij formation, sirki, pirkoh limestone, drazinda, lagoonal, habib rahi, diagenetic, phreatic, eugenetic, telogenetic, mesogenetic stages, microvuggy, intrapartcle, microcystalline dolomite, ostracod grainstones, nari formation, habib rahi limestone member, sirki member, pirkoh limestone member, drazinda member

Kirthar formation (Middle to Late Eocene) is conformably underlain by Ghazij formation (Early Eocene) and is unconformably overlain by Nari formation (Oligocene) in Sulaiman sub-basin of Pakistan where it is comprized of four lithologic units: Habib Rahi limestone member, Sirki member, Pirkoh limestone and marl member, Drazinda member. These units are persistently present with variable thickness in study area.

Nine major microfacies are recognized in 211 core and 248 outcrop samples from eleven (11) limestone horizons recorded in the Kirthar formation. The four lithologic units are end result of sea-level fluctuations in combination of tectonic events. Thick alabaster in the upper part of the Ghazij formation represents late Early Eocene regressive cycle resulting in restricted, evaporitic basin. Middle Eocene is the period of transgression during which the Kirthar formation is deposited in shelf setting extending from semi-restricted inner (lagoonal) to open marine outer part (shallow carbonate shoal/platform edge setting to deep basinal environments).The Habib Rahi limestone and Pirkoh limestone & marl are transgressive to highstand units deposited in 'catch-up' to 'keep-up' pattern while thick shales of Sirki and Drazinda members are generally prograding units.

The limestones members experienced shallow to deep burial diagenetic environments involving marine phreatic, freshwater phreatic (super-saturation and under-saturation) and mixed marine diagenetic conditions. Algal encrustation and bioerosion were active under marine phreatic environments. Primary porosities were destroyed during overburden compaction while secondary moldic and fracture porosities were developed by dissolutions which later were occluded by successive calcite and dolomite cementation phases in eugenetic stage. Chemical compaction( pressure dissolution) was active in deep burial realm in mesogenetic stage. Present outcrops are subjected to sub-aerial conditions through uplifting in telogenetic stage.

The microvuggy matrix and solution enlarged secondary intrapartcle porosities are common to abundant in core samples of Mari gas field while rare to sparse (2-5%) secondary moldic and vuggy porosities are ohserved in core as well as at outerops. These porositie are generally fabric selective and facies related and are produced by dissolution phase in deep burial diagentic conditions occurring in mesogenesis zone. The nature of aggressive fluids responsible for porosity development are indeterminate.

The reservoir characters of the Habib Rahi limestone member should be well developed in the north and southern part of the Sulaiman sub-basin where potential facies for porosity development (platform edge/shoal/lagoonal) are thickly deposited. Same is the case with the Pirkoh limestone & marl member which has good reservoir potential in south western and southern parts of the study area. The source rock potential facies (deep, open marine shelf basinal) are thickly deposited in the central part of the basin, where the environments were conductive for deposition of organic rich oil shale horizons.

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23711.78 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
976.13 KB
2 1 Introduction 1
251.77 KB
3 2 Methods And Techniques 2
189.5 KB
4 3 General Geology Of The Study Area 4
1206.24 KB
  3.1 Physiography 4
  3.2 Geological History 4
  3.3 Major Tectonic Elements 7
  3.4 Hydrocarbon Potential 8
5 4 Previous Work On Kirthar Formation 9
278.88 KB
6 5 Stratigraphic Description Of Lithologic Units And Their Spatial Distribution 11
1298.45 KB
  5.1 Shale With Alabaster Member 11
  5.2 Habib Rahi Limestone Member 12
  5.3 Sirki Member 13
  5.4 Pirkoh Limestone And Marl Member 13
  5.5 Drazinda Member 14
  5.6 Nari Formation 14
  5.7 Description Of Plates 16
7 6 Field Investigations 18
2440.15 KB
  6.1 Outcrop Studies 18
  6.2 Subsurface Studies 25
  6.3 Description Of Plates 28
8 7 Microfacies Analysis 30
3003.93 KB
  7.1 Microcystalline Dolomite 30
  7.2 Radiolarian Wacketones 31
  7.3 Globigerinids Wacke To Packstones 32
  7.4 Formineral Wackestones To Packstones 34
  7.5 Molluscan Wacke To Packstones 35
  7.6 Green Algal Packstones 36
  7.7 Bioclastic Formainiferal Packstone To Grainstones 37
  7.8 Formainiferal Grainstones 39
  7.9 Ostracod Grainstones 41
  7.10 Description Of Plates 42
9 8 Depositional Facies , Environments, Sequences And History 48
1392.58 KB
  8.1 Deep, Open Shelf Basinal Facies 48
  8.2 Open Sea Shelf Facies 50
  8.3 Carbonate Sand Shoals/ Plateform Edge Facies 51
  8.4 Semi-Protected Marine ( Logoonal ) Shelf Facies 52
  8.5 Restricted Marine (Inner) Shelf Facies 54
  8.6 Depositional Sequences And History 55
10 9 Pre-And Syn -Depositional Alterations 58
361.32 KB
  9.1 Iron Coating 58
  9.2 Algal Encrustation 58
  9.3 Intraskeletal Bioerosion And Microbial Micritization 58
  9.4 Internal Sedimentation/ Geopetal Infills 59
  9.5 Bioturbation 59
  9.6 Description Of Plates 60
11 10 Diagenesis And Diagenetic Environments 61
3003.26 KB
  10.1 Cementation 61
  10.2 Neomorphism 64
  10.3 Dissolution 65
  10.4 Replacements 66
  10.5 Mechanical Compaction 70
  10.6 Organic Matter Diagenesis 72
  10.7 Description Of Plates 72
12 11 Dianenetic Sequences And Patterns 78
653.85 KB
  11.1 Genaralized Diagenetic Sequence 78
  11.2 Diagenetic Pattern For Deep, Basinal Shelf Facies 80
  11.3 Diagenetic Pattern For Open Sea Shelf Facies 80
  11.4 Diagentic Pattern For Platform Edge/ Shoal Facies 81
  11.5 Diagentic Pattern For Lagoonal Shelf Facies 82
  11.6 Diagenetic Pattern For Restricted Inner Shelf Facies 82
13 12 Porosity Development , Reservoir And Source Rock Potential 84
1142.36 KB
  12.1 Porosity Developments 84
  12.2 Reservoir Potential 86
  12.3 Source Rock Potential 87
  12.4 Description Of Plates 89
14 13 Clay Mineral Analysis 91
387.99 KB
  1.3.1 Methodology 91
  13.2 Analytical Results And Interpretations 92
15 14 Conclusion 94
356.8 KB
16 15 References 98
7110.8 KB