SPATIAL BIOSTRATIGRAPHY OF NW PAKISTAN

A DISSERTATION

Submitted to the Faculty of Miami University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Geology

By

Naseer Ahmed Shafique Miami University Oxford, Ohio 2001

Dissertation Director: Dr. Brian S. Currie

MIAMI UNIVERSITY - THE GRADUATE SCHOOL CERTIFICATE FOR APPROVING THE DISSERTATION

We hereby approve the dissertation of Naseer A. Shafique Candidate for the Degree: Doctor of Philosophy

______Dr. Brian S. Currie, Advisor

______Dr. Richard Beck, External Reviewer

______Dr. Mark Boardman, Internal Reviewer

______Dr. Yildirim Dilek, Internal Reviewer

______Dr. A. S. Montagu, Graduate School Representative

ACKNOWLEDGMENTS

All praises to Almighty God, whose mercy enabled me to complete this study.

The author wishes to thank Miami University who provided stipend and laboratory space in support of my studies, Geological Society of America for providing funds for additional sampling of the critical stratigraphic horizons. The Hydrocarbon Development

Institute of Pakistan provided logistical support. Amoco Production Company and

Reservoirs Incorporated furnished unpublished petrographic and stratigraphic data.

Thanks are due to Dr. Richard A. Beck, whose marvelous interest in the

Himalayan Geology provided me the opportunity to come in USA and complete the work on Waziristan biostratigraphy. In the final stages of this work, unfortunately Dr. Beck had to leave Miami University, but thanks to Dr. Brian Currie who spent a lot of time to review the manusript and by virtue of that I am being able to complete this dissertation.

This dissertation is dedicated to my beloved parents, especially to my mother who could not wait for the completion and left this world for good.

TABLE OF CONTENTS

Acknowledgments...... 3 Abstract ...... 10 1. CHAPTER 1 ...... 12 Problem Statement ...... 13 Previous Work...... 14 2. CHAPTER 2 ...... 16 Introduction ...... 17 Regional Structural/Stratigraphic Framework ...... 17 Tectonostratigraphic Units ...... 20 Triassic to Cretaceous parautochthonous Indo-Pakistani shelf strata ...... 20 Ophiolitic Complex Nappes...... 23 Deep marine sedimentary allochthons ...... 23 Early Tertiary strata...... 23 Late Tertiary non-marine foreland basin strata...... 23 Objectives and Methods...... 23 Identification of Microfossils...... 24 Zonal Scheme...... 24 Chronobiostratigraphy...... 24 Generalized Lithostratigraphy and Biostratigraphy ...... 26 Triassic-Cretaceous Indo-Pakistani shelf strata ...... 26 Triassic strata...... 26 Jurassic strata...... 30 Cretaceous strata ...... 36 Waziristan Ophiolite Complex...... 39 Allochthonous Deep Water Strata...... 40 Early Tertiary Strata...... 48 Eocene Strata...... 52 Summary of Biostratigraphic Zones ...... 58 Jurassic Strata...... 58 Cretaceous Strata...... 59 Paleocene Strata ...... 62 Eocene Strata...... 64 Tectonic Contrls on Basin Development ...... 67 Conclusions ...... 79 3. CHAPTER 3 ...... 80 Introduction ...... 81 Regional Tectonic Framework...... 82 Methods and Data...... 82 Biostratigraphic Methods ...... 82 Sample Preparation ...... 82 Identification of Microfossils...... 82 Zonal Scheme...... 85 Chronobiostratigraphy...... 85 Paleoenvironment...... 85

Stratigraphy of the Mughal Kot Gorge ...... 87 Sembar Formation:...... 87 Radiometric Constraints on the Ophiolites ...... 90 Results ...... 90 Biostratigraphic Data...... 90 Biozones...... 90 Bioevents...... 94 Paleoenvironment and Bathymetric Distribution...... 94 Summary of Biostratigraphic Events ...... 95 Interpretation ...... 101 Conclusions ...... 101 4. CHAPTER 4 ...... 102 Introduction ...... 103 Method and Data ...... 104 Overview ...... 104 Building a Spatial Database ...... 105 Attributes of Geological & Analytical Data...... 105 Digitization of Previous Maps...... 105 Remote Sensing and Image Processing...... 107 Data Processing...... 112 Integration Model...... 113 Data Management ...... 113 Data Visualization...... 114 Thematic Layering ...... 114 Previous Map Themes...... 114 Remote Sensing Themes ...... 116 Biostratigraphic Analysis Themes ...... 118 Limitations ...... 118 New Map Construction ...... 118 Statistical Comparison with Previous Maps ...... 121 Conclusions ...... 129 References ...... 130

LIST OF FIGURES

Figure 2-1: Regional geologic map of NW Pakistan and Eastern Afghanistan (after Beck et al., 1996b; Lawrence et al., 1991; Cassaigneau, 1979; Tapponnier et al., 1981; Mattauer et al., 1978)...... 18 Figure 2-2: Tectonostratigraphic map showing the major units of the NW Pakistan and eastern Afghanistan area. The map is based on Kaever (1967), Ganss, (1970), Meissner (1975), Cassaigneau (1979) and present study...... 21 Figure 2-3: Generalized cross section showing structural configuration of the study area (Vertical exaggeration is ~ 2X). See Fig. 2-2 for location...... 22 Figure 2-4: Zonal Correlation used in this study, (1) numerical ages, chrons and polarity are assigned (after Harland et al., 1990); (2) planktonic foraminiferal zonation scheme for Paleocene and Eocene by Berggren et. al., (1995) and for Cretaceous by Caron (1985); (3) larger benthic association scheme adopted after (Weiss, 1988); (4) Radiolaria zones assigned (after Sanfilippo and Riedel, 1985) ...... 25 Figure 2-5: Composite stratigraphic column of Triassic to Eocene strata exposed in the study area...... 27 Figure 2-6: Map showing prominent geographic and sample localities in the study area.28 Figure 2-7: Outcrop map of Triassic to Cretaceous passive margin strata (Sources, Hemphill and Kidwai, (1975); Meissner et al., (1975) and present study) ...... 29 Figure 2-8 a: Outcrop of Waziristan and Khost ophiolites (after Robinson, 2000 and Gnos, 1998)...... 41 Figure 2-9: Outcrop map of deep marine Middle to Late Cretaceous allochthonous units (after Gnos, 1998 and present study)...... 43 Figure 2-10: Outcrop map of Lower Tertiary strata (after Hemphill and Kidwai, 1974; Meissner et al., 1975; Gnos et al., 1998 and present study)...... 49 Figure 2-11: Time stratigraphic correlation of sedimentary tectonostratigraphic units of the study area...... 60 Figure 2-12: Foraminiferal Distribution of Jurassic strata identified in Waziristan and Kurram areas. Numerical ages are assigned (after Harland et al., 1990)...... 61 Figure 2-13: Foraminiferal Distribution of Cretaceous strata studied in the Waziristan and Kurram areas. Numerical ages are assigned (after Harland et al., 1990)...... 63 Figure 2-14: Foraminiferal Distribution of Cretaceous Kahi Melange strata studied in the Kurram and Thal areas. Numerical ages are assigned (after Harland et al., 1990)... 65 Figure 2-15: Foraminiferal Distribution of Paleocene strata studied in the Waziristan and Kurram areas. K.K.O.M = Kahi Kurram Orakzai Melange and K.M. = Kahi Melange. Numerical ages are assigned (after Harland et al., 1990)...... 66 Figure 2-16: Foraminiferal Distribution of Early Eocene identified in Waziristan and Kurram areas. Numerical ages are assigned (after Harland et al., 1990)...... 68 Figure 2-17: Foraminiferal Distribution of Early to Middle Eocene strata studied in the Waziristan and Kurram areas. Numerical ages are assigned (after Harland et al., 1990)...... 69 Figure 2-18: Depositional history of the Indo-Pakistani passive margin strata exposed in Waziristan and Kurram, deduced from the characteristic foraminiferal, radiolarian assemblages and palynomorphs observed in the study area...... 70

Figure 2-19: Depositional history of allochthonous strata exposed in the study area, deduced from the characteristic foraminiferal, radiolarian assemblages and palynomorphs observed in the study area...... 72 Figure 2-20: Depositional history of the syn and post collision strata exposed in the study area, deduced from the characteristic foraminiferal, radiolarian assemblages and palynomorphs observed in the study area...... 74 Figure 2-21: Paleogeographic map and cross-section of Waziristan and Kurram areas during Triassic to Middle Cretaceous time...... 76 Figure 2-22: Paleogeographic map and cross-section of Waziristan and Kurram areas during Late Cretaceous ophiolite obduction...... 77 Figure 2-23: Paleogeographic map and cross-section of Waziristan and Kurram areas during Paleocene-Eocene time...... 78 Figure 3-1: Simplified geologic map of Pakistan showing regional structural elements and study area. M.K.T., Main Karakoram Thrust; M.M.T., Main Mantle Thrust; P.P.T., Pir Punjal Thrust; M.B.T., Main Boundary Thrust; Sulaiman F.T.B. Sulaiman Fold and Thrust Belt; J.M. ARCH, Jacobabad Mari Arch; O.N.F., Ornach Nal Fault; WO, Waziristan ophiolites; KO, Khost ophiolites; MBO, Muslimbagh ophiolites; BO, Bela ophiolites (after Beck et al., 1996b)...... 83 Figure 3-2: Geological Map of the Mughal Kot Gorge area (after Hemphill and Kidwai, 1975). Lithologic symbols used in this map are adopted in all other figures...... 84 Figure 3-3: Zonal Correlation used in this study, (1) numerical ages, chrons and polarity are assigned (after Harland et al., 1990); (2) planktonic foraminiferal zonation scheme for Paleocene and Eocene by Berggren et. al., (1995) and for Cretaceous by Caron (1985); (3) larger benthic association scheme adopted after (Weiss, 1988); (4) Radiolaria zones assigned (after Sanfilippo and Riedel, 1985) ...... 86 Figure 3-4: Cretaceous Foraminiferal Distribution Chart of Mughal Kot Section. Numerical ages are assigned (after Harland et al., 1990)...... 92 Figure 3-5: Tertiary Foraminiferal Distribution of Mughal Kot Section. Numerical ages are assigned (after Harland et al., 1990)...... 93 Figure 3-6: Sea level history at Mughal Kot Section deduced from P:B ratio of Foraminiferal Biostratigraphy. Numerical ages are assigned (after Harland et al., 1990)...... 96 Figure 3-7: Subsidence history at Mughal Kot Section deduced from the Foraminiferal Biostratigraphy. Three subsidences, passive margin, ophiolite obduction related and subsequent collision related subsidences are observed. Numerical ages are assigned (after Harland et al., 1990)...... 98 Figure 3-8: Regional biostratigraphic compilation of the Mughal Kot section and Waziristan area, (1) metamorphic ages based on single crystal Ar/Ar radiometric studies of hornblende in the metamorphic sole of the Waziristan ophiolite (90-96 Ma) (Gnos, 1997 and 1998); (2) radiometrically dated cross-cutting relationship (80 Ma) (Gnos, 1997 and 1998). Numerical ages are assigned (after Harland et al., 1990)...... 99 Figure 3-9: Localities of olistoliths found in the Mughal Kot Formation in the NW Pakistan (after Burris et al., 1996)...... 100 Figure 4-1: Cross plot of DN values; a) before stretching; b) after stretching (Rothery, 1987)...... 111

Figure 4-2: Data visualizing in ArcView, the data associated with particular point or polygon theme can be seen by clicking on the view...... 117 Figure 4-3: Band combination of 7,5,4 in RGB to differentiate between shale and limestone units...... 119 Figure 4-4: Ratio Image of 3/4, 5/4, 7/5 in RGB to differentiate limestone, and opiolite lithologies...... 120 Figure 4-5: First three principal components of TM bands 4, 5 and 7 bands in RGB to distinguish sedimentary strata and ophiolites...... 122 Figure 4-6: Decorrelation stretch image of 7, 5, 4 band in RGB. This image is helpful in determining the ophiolite spatial boundaries and in distinguishing different types of limestone (Rothery, 1987)...... 123 Figure 4-7: Biostratigraphic data attributes, Sample No., Location, Formation, Lithology, Age and Paleoenvironment visualized in ArcView ...... 124 Figure 4-8: Map constructed from previously existing maps of the area, which placed in the view as backdrop and polygons of each lithological units were constructed.... 125 Figure 4-9: Map constructed from the previous map themes for statistical comparison with new map, the significant changes occurred in the Triassic-tertiary undifferentiated and Mesozoic-Tertiary undifferentiated areas...... 127 Figure 4-10: New GIS based map showing lithostratigraphy, biostratigraphy and paleoenvironment of the region...... 128

LIST OF TABLES

Table 3-1: Rate of Sedimentation in the Mughal Kot Gorge estimated from the sedimentary thickness vs. depositional time...... 97 Table 4-1: A sample list of the individual polygons used in the GIS of the study area. A code # is assigned for common attributes, such as of lithology and age, for each map unit...... 106 Table 4-2: Colors shown by rocks in a TM Landsat band 7, 5, 4 in RGB (after Rothery, 1987)...... 110 Table 4-3: Colors of Decorrelation stretched TM images (after Rothery, 1988)...... 115 Table 4-4: Statistical comparison of area changed from previous maps to the new GIS based map...... 126

Spatial Biostratigraphy of NW Pakistan

by

Naseer A. Shafique

ABSTRACT

Mesozoic to Cenozoic biostratigraphy of NW Pakistan has been conducted in order to document the temporal and spatial relationship between different marine strata with the help of remote sensing and Geographic Information Systems (GIS). These relationships were then used to help distinguish different tectonostratigraphic units in the

Waziristan and the Kurram areas located at the northwestern margin of the Indo-Pakistani craton.

Extensive biostratigraphic work in the Waziristan and Kurram areas enabled to distinguish five tectonostratigraphic units and two significant unconformities in the study area. Different foraminiferal zones from Early Jurassic to Middle Eocenewere developed, although due to random samples these zones are not continuous in the sedimentary record. However continuous biozonation from the Late Paleocene P4 to the Early Eocene

P9 (Bolli, 1985) biozone was observed.

It is observed that the Santonian stage is generally missing in the sedimentary sequence, and it is only found in the olistoliths. This implies that during the Campanian stage there was instability in the shelf due to ophiolite obduction, which caused the displacement of the Santonian strata.

The absence of Early Paleocene (Zone P1 – P3) microfauna is suggested by rapid subsidence of the NW Indian shelf beginning in the early Paleocene. Moreover, index fossils for the Pα, P1a, b, c, d, P2 and P3 biozones are absent in the mélange of the Thal

area suggesting regional uplift during the Paleocene. The presence of Planorotalites pseudomenardii P4 zone microfauna above the unconformable Upper Cretaceous Kahi mélange strata suggest the India-Asia collision age between 58 Ma - 56 Ma.

Foraminiferal biostratigraphy of upper Cretaceous olistoliths was conducted from the Mughal Kot gorge, Baluchistan, Pakistan in order to reveal the depositional history of

Late Santonian aged (Dicarinella asymmetrica zone) olistoliths and associated upper

Cretaceous to early Tertiary Indo-Pakistani shelf strata. These olistoliths are embedded in uppermost Campanian strata of the Mughal Kot Formation. Similar olistostromes are found at approximately the same stratigraphic level across a broad region of NW

Pakistan. These olistostromes are similar in age to radiometrically constrained deformation in the Zhob and Waziristan ophiolites 50 and 90 km to the west and northwest respectively and may record incipient underthrusting of the NW Indo-Pakistani craton beneath oceanic crust now in Waziristan and northern Baluchistan. This

Campanian event precedes stratigraphically constrained Paleocene and Early Eocene deformation in Parachinar, Orakzai and the Attock-Cherat Ranges, which is interpreted as the collision of NW Indo-Pakistan with Asia and the Kabul Block.

A turbiditic depositional environment of the Mughal Kot Formation was developed due to the regional collapse of the NW Indo-Pakistani shelf margin during the

Late Campanian (G. calcarata zone ~ 80 – 74 Ma), possibly as a result of ophiolite obduction as the Indo-Pakistani plate moved beneath Tethyan oceanic crust.

1. CHAPTER 1

INTRODUCTION

PROBLEM STATEMENT The tectonic development of the Himalayas is primarily related to the collision of the Indo-Pakistani and Eurasian plates. In addition to being one of the major tectonic events in Earth history, the development of the Himalayas also has implications to changes in the earth’s geochemical and climatic system (Rowley, 1996; Beck et al., 1995b), paleooceanography (Stille, 1992), paleoclimate, faunal extinction (Jaegger et al., 1989) and global plate motions (Patriat and Achache, 1984). Biostratigraphic control is necessary to determine the tectonostratigraphy of a region and the chronology of deposition. Biostratigraphic data can help constrain ages of strata, interpret depositional environments and reconstruct paleogeography. These determinations, in turn, imply the stratigraphic and/or tectonic position of strata and are necessary for the construction of properly constrained geologic histories. One of the primary processes involved in the initial stages of continent-continent collision involves the obduction of oceanic crust and the development of ophiolite belts. Ophiolite belts are thought to represent collisional sutures along which remnants of subducted oceanic crust are thrust onto continental crust of the colliding plate (Moores and Twiss, 1995). In one model of ophiolite obduction, part of the subducting oceanic block detaches, presumably along a pre-existing fault or ridge axis, and is thrust onto the continental margin as the rest of the slab continues to subduct. This model has been proposed to explain ophiolite belts in the northwestern Himalaya of Pakistan. In this scenario, collision of the Kohistan island arc with Asia caused a temporary shift of subduction southward to a spreading center north of the Indian craton. As north directed subduction progressed, the subduction zone impinged on the northwestern margin of the Indian craton. As a result northwestern Pakistan was thrust beneath the Mesozoic oceanic crust and a volcano-sedimentary complex. This underthrusting generated an ophiolite- radiolarite belt now known as the Waziristan and Khost ophiolite (Coleman, 1981). In order to better understand the complex mechanism of continent-continent collision it is necessary to elucidate the timing and nature of ophiolite obduction. By thoroughly examining ophiolitic and adjacent sedimentary sequences exposed in the suture between the two continents, some fundamental questions concerning the timing of the ophiolite obduction and the overall kinematics of India-Asia collision can be answered. Despite years of research, however, the timing of ophiolite obduction in the western Himalayas is still the subject of debate (Beck et al., 1995). One school of thought suggests the obduction of oceanic lithosphere occurred along the western margin of the Indo-Pakistani craton during the Late Cretaceous (Stoneley, 1974), while others interpret this event as occurring during Paleocene time (Allemann, 1979; Cassaigneau, 1979; Mahmood et al., 1996). Each of these hypotheses however implies very different Late Cretaceous - Paleocene geologic history and tectonic configuration for the region. Moreover, recent studies suggest that the timing of ophiolite obduction may have been diachronous within the westernmost segment of India-Asia suture zone. For example,

along the southern part of the western margin, radioisotopic and micropaleontological evidence indicate a Paleocene-Eocene age of obduction (Gnos et al. 1998). Along the northern part of the western margin however, similar evidence suggests that obduction occurred during the Late Cretaceous (Beck et al. (1996) and Gnos pers. comm. (1998).

PREVIOUS WORK Neo-Tethyan ophiolitic and/or oceanic remnants are recognized in four crustal structure zones throughout the western and northern Himalayas. From west to north these regions include Waziristan (Brookfield, 1993), the Khost, Kabul, and Jalalabad areas (Andrieux and Brunel, 1977; Tapponier et al., 1981; Brookfield, 1993), and the outcrops along Indus-Tsangpo Suture (Jan et al., 1983a; Tahirkheli, 1979; Bard et al., 1980 and Bard, 1983). Of these, the ophiolites along the Indus-Tsangpo Suture Zone, north of the greater Himalayas, have received the most attention (Gansser, 1964; Fuchs, 1977; Burg and Chen, 1984; Searle, 1986; Keleman et al., 1988; Robertson and Degnan, 1993; Brookfield, 1993; Garzanti, 1993 and 1998; Rowley, 1996). Due to the complex geology of the region, however, these studies have created little consensus as to the obduction history of the area. For example, the lack of definitive stratigraphic relationships due to subsequent subduction, erosion and deformation of ophiolites resulted in different ages of obduction from Middle Cretaceous to Middle Eocene in the region. In the suture zone along the northwestern margin of India relatively little is known about the history of ophiolite obduction. This has been primarily due to the remote setting of the area and political unrest in the region (Beck et al., 1996; Robinson, 2000). Stonely (1974) speculated that obduction of ophiolites on the northwestern margin of Indo-Pakistani craton took place during the Campanian-Maastrichtian interval. Alleman (1979), based on his stratigraphic work in Baluchistan, suggested the ophiolite emplacement in the Paleocene. The studies of Cassaigneau (1979) in Afghanistan suggested that the obduction of the Khost ophiolites occurred during the Paleocene. Treloar and Izatt (1993) concurred with this Paleocene age assessment but noted large gaps in the knowledge of the region. Coleman (1981) studied the Middle Cretaceous volcano-sedimentary complex and concluded that the Waziristan and Khost ophiolites were emplaced on to northwestern corner of Indo-Pakistani craton during the late Santonian through middle Maastrichtian time. Beck (1996) provided the first in depth study of the Waziristan and Kurram areas. Based on a stratigraphic compilation and regional structural synthesis, Beck (1996) postulated that the Waziristan ophiolite was obducted during Turonian to Maastrichtian (Late Cretaceous). Across the orogen, recent estimates of the timing of India-Asia collision vary from 65 Ma to 45 Ma. These estimates are mainly based on work done on the northern Himalayas (Searle et al., 1987; Dewey et al., 1989; Le Pichon et al., 1992; Chen et al., 1993; Rowley, 1996). The ambiguity again results from the complex geology of southern Tibet and the difficulties of identifying geologic features associated with the initial collision process (Robertson and Degnan, 1993). The work of Beck (1995a) on NW Pakistan produced stratigraphic evidence for Paleocene collision between NW Indo-Pakistani craton and Asia. The present study has been conducted in order to refine the age and depositional history of the strata involved in ophiolite obduction in northwestern Pakistan through the use of high resolution

foraminiferal and radiolarian biostratigraphy, remote sensing and Geographic Information System technology. Previous investigations on the timing of ophiolite obduction and initial continent- continent collision have been hampered by the extensive nature of post-collisional deformation in the Himalayas and by the poor biostratigraphic control of the rocks involved. In order to clarify these issues, the present study provides the biostratigraphic framework for the Late Cretaceous through Early Eocene sedimentary succession present in less deformed areas of Waziristan and Kurram Agencies situated at the junction of the western transform and northern convergent boundaries of the Indo-Pakistani plate. Approximately 400 samples collected from allochthonous sedimentary strata, Waziristan and Kurram areas and the Indo-Pakistani shelf sequence, Mughal Kot section, Baluchistan was studied. These data provide the biostratigraphic framework for the Late Cretaceous through Middle Eocene sedimentary sequences of the region. The goals of this study are to provide the basic litho- and biostratigraphic information necessary to constraint the age of strata in the region, determine the timing of major unconformities, and provide age constraints for cross-cutting structural relationships in the NW Pakistan region. This basic stratigraphic information will help determine the timing of deformation and sedimentation in the area. In turn, this new chronology of deformation will help reconstruct the geologic and tectonic histories of the region. This dissertation consists of three parts. Chapter 2 presents a detailed biostratigraphy of Waziristan and Kurram areas in northwestern Pakistan. Paleogeographic analysis of biostratigraphically constrained tectonostratigraphic units are also presented in this chapter. Chapter 3 presents the biostratigraphy of the Mughal Kot Indo-Pakistani shelf sequence and the depositional age of associated olistoliths. Chapter 4 integrates the refined bio and lithostratigraphic data with remote sensing data from NW Pakistan in order to present a geographic information system (GIS) based map of the region. The key finding of this study is that olistoliths contained in Indo-Pakistani continental shelf strata of this area were deposited in younger strata during ophiolite obduction. These Late Cretaceous-aged olistoliths are well exposed in the Mughal Kot gorge in northwestern Pakistan. The foraminiferal age assignment and paleoenvironmental analysis of the olistoliths and their relation to the ophiolite obduction has been used to clarify the tectonic history of northwestern Pakistan. In particular, both stratigraphic and other geochronologic data suggest ophiolite obduction began in the region during Campanian time. If the hypothesis is correct, ophiolite emplacement in this area may have taken place tens of millions of years before India-Asia collision and before ophiolite obduction along the southern segment of the western margin of the Indo- Pakistani craton.

2. CHAPTER 2

BIOSTRATIGRAPHY OF WAZIRISTAN AND KURRAM AREAS, NW PAKISTAN AND ITS IMPLICATIONS FOR TIMING OF OPHIOLITES OBDUCTION AND INDIA-ASIA COLLISION.

INTRODUCTION

The biostratigraphy of sedimentary terranes can be an important tool in deciphering the tectonostratigraphy of suture zones and the chronologies of their construction. Biostratigraphic data help constrain ages of strata, determine depositional environments and reconstruct paleogeography. As such these determinations are necessary to properly construct the geologic and tectonic history of collisional orogenic belts. The goal of the study is to present biostratigraphic evidence to constrain the timing of ophiolite obduction and collision along the western margin of the Indo- Pakistani plate. This chapter presents biostratigraphic data for Mesozoic/Cenozoic rocks from the Waziristan/Kurram Tribal Agencies of NW Pakistan (Fig. 2-1). This region is situated at the junction of the northern convergent and western transform margins of the Indian plate. The rocks of Waziristan and Kurram areas record Mesozoic-Cenozoic passive margin deposition, ophiolite emplacement and continental collision along the NW margin of the Indian craton (Mattauer et al., 1978a; Cassaigneau, 1979; Tapponnier et al., 1981; Beck et al., 1995a,b). This chapter documents the biostratigraphic age constraints and depositional history of sedimentary strata from Triassic to Early Tertiary of NW Indo-Pakistani plate margin. Biostratigraphic analysis of more than 400 samples from the Waziristan and Kurram Agencies were conducted as part of this study. Samples were also collected from relatively undeformed Indo-Pakistani shelf strata from the Zhob area to the south in order to provide further stratigraphic control. The study area was subdivided into the Waziristan, Kohat and Kurram areas in order to simplify regional differences in stratigraphic nomenclature.

REGIONAL STRUCTURAL/STRATIGRAPHIC FRAMEWORK The Waziristan and Kurram areas are located near the junction of the northwest terminus of the world’s highest mountain range, the Himalayas, and one of the world’s largest continental transforms, the Chaman Fault (Fig. 2-1). Four major tectonic features associated with the Himalayan orogeny, the Frontal Fold and Thrust Belt, Allochthonous deep marine sedimentary nappes, the Zhob-Waziristan-Khost ophiolite complex, and the Katawaz Basin are the key elements controlling the stratigraphic framework of the study area.

Figure 2-1: Regional geologic map of NW Pakistan and Eastern Afghanistan (after Beck et al., 1996b; Lawrence et al., 1991; Cassaigneau, 1979; Tapponnier et al., 1981; Mattauer et al., 1978).

Frontal Fold- and Thrust Belt Waziristan forms the northwest part of the Indus Basin and is geographically situated at the northern edge of the Sulaiman Range. The area is a part of the fold-and- thrust system that exists along the western margin of the Indo-Pakistani plate (Fig. 2-1). The substantial fold and thrust system is bounded on the west by a zone of ophiolites, the Chaman Fault, and the rocks of Katawaz basin. The fold-and-thrust belt is bounded to the northeast, east and southeast by the Indus basin, and to the southwest and west by the Jacobabad-Mari Arch and the Kirthar Range (Khurshid Akbar et al., 1992). The fold-and-thrust belt in Waziristan is the product of the ongoing collision between the Indo-Pakistani and Eurasian plates. The broad width (250-km) of the thrust belt in this location suggests that the overall structure is thin-skinned in nature, where rocks have been thrust to the southeast on a weak decollement above a low angle, northwestward dipping basement (Sarwar and DeJong, 1979). However, it is unknown if the regional basal decollement is within Eocambrian evaporites known to underlie the Salt Range and Potwar Plateau regions, or if it is within another zone of weakness. Structural complexities in the Sulaiman region also owe their origin to oblique convergence of the Indo-Pakistani plate along the Chaman fault system, which is interpreted as a complex transform zone between the Makran subduction zone in the south, and the Himalayan convergence zone to the north. Pre-existing basement structures, which developed along the western edge of the Indo-Pakistani plate during Mesozoic rifting of Gondwanaland, may also influence the structural configuration of the Sulaiman range (Khurshid Akbar et al., 1992). Rocks exposed in the fold and thrust belt consist primarily of post-collisional, Late Tertiary Nonmarine foreland basin deposits, and Triassic to Eocene shallow to deep marine strata originally deposited along the Northwestern margin of the Indo-Pakistani craton.

Allochthonous Ophiolitic and Deep Marine Rocks West of the fold and thrust belt in the study area is a regionally extensive belt of ophiolitic rocks and associated deep marine strata (Fig. 2-2). These rocks lie along the suture zone between the Eurasian belt and Indo-Pakistani plate. In Waziristan, ophiolitic and deep marine sedimentary units are contained in thrust nappes that have been emplaced over Mesozoic rocks of the Indian shelf and outer margin. The nappes include, from structurally lowest to highest: 1) a nappe of pillow basalts, Aptian-Albian to Campanian radiolarian chert, and olistoliths of Upper Jurassic to Cretaceous limestone contained in matrix of Campanian shale; 2) a thrust sheet of ophiolitic rocks containing serpentinized harzburgite, gabbroic/dioritic rocks and sheeted dykes; and 3) a regionally extensive nappe of Jurassic-Upper Cretaceous deep marine sedimentary rocks (Kaever, 1967a: Meissner et al., 1975: Beck et al., 1996). All three-thrust nappes were intensely folded in Maastrichtian/Early Paleocene time and were subsequently overlain by Middle Paleocene and Early Eocene strata (Gnos et al., 1998).

Katawaz Basin The Katawaz basin is located northwest of Bannu and Waziristan basins in Pakistan and adjacent Afghanistan (Fig. 2-1 & 2). It is more than 700 km in axial length and has a maximum width of about 200 km. Deformational structures in rocks of the Katawaz basin structures are mostly transpressional along its western edge compressional towards the east (Qayyum, 1996). A major strike slip fault, the Chaman fault, separates the Katawaz basin from the Afghan Block (Lawrence, 1979; Lawrence, 1981; Treloar and Izatt, 1993). Katawaz strata are more than 8000 km thick and interpreted as being deposited in submarine fan, deltaic, and fluvial environments within and along the margin of a remnant ocean basin during Eocene to Early Miocene time (Qayyum, 1996). During this time the basin was one of the primary depocenters for sediments derived from initial uplift of the Himalayan orogeny. Katawaz deposition ended during the Early Miocene as the remnant ocean was incorporated into the fold and thrust belt along the western margin of the Indo-Pakistani plate. Katawaz rocks were later deformed by strike-slip displacement along the Chaman Fault (Qayyum, 1996).

TECTONOSTRATIGRAPHIC UNITS Rocks in Waziristan and Kurram can be divided into five tectonostratigraphic units on the basis of similarities in tectonic settings during the time of deposition (Fig. 2- 2)(Beck et al., 1996; Robinson et al., 2000). These five units consist of: 1) Triassic to Cretaceous strata originally deposited along the continental shelf and slope of the Indo- Pakistani plate; 2) Ophiolitic rocks consisting of serpentinized harzburgite, gabbroic/dioritic intrusions, sheeted dikes and Cretaceous radiolarian chert, shale and olistostromes. These rocks originally were formed and deposited within the Tethyan ocean basin, were subsequently obducted onto Indian plate margin during latest Cretaceous time; 3) Allochthons of deep marine rocks that were thrust on to the Indo- Pakistani shelf margin following initial ophiolite obduction. These strata were originally deposited on oceanic crust; 4) Early Tertiary strata deposited during the initial stages of collision between India and Eurasia; 5) Late Tertiary non-marine foreland basin strata deposited inboard of the present-day fold and thrust belt following its initial development (Fig. 2-3).

Triassic to Cretaceous parautochthonous Indo-Pakistani shelf strata In the study area, Late Triassic to Late Cretaceous aged carbonates and siliciclastics originally deposited along the northwest margin of the Indo-Pakistani plate include the Khan Kot Formation, Nimar Azrai Formation, Danawat Formation, Zer Ghar Limestone, Razani Formation, Srapa Mela Formation, Zargaran Shale, Samana Suk Formation, Chichali Formation, Chorai Nallah/Goru Formation and Darsamand Limestone. These units are predominantly comprised of carbonates sandstone and shale and contain facies changes towards the west that suggest typical passive margin, shelf to slope environments. In general these Mesozoic strata thicken westward.

Figure 2-2: Tectonostratigraphic map showing the major units of the NW Pakistan and eastern Afghanistan area. The map is based on Kaever (1967), Ganss, (1970), Meissner (1975), Cassaigneau (1979) and present study.

Figure 2-3: Generalized cross section showing structural configuration of the study area (Vertical exaggeration is ~ 2X). See Fig. 2-2 for location.

Ophiolitic Complex Nappes Thrust sheets containing ophiolitic rocks are exposed in the Zhob, Waziristan and Kurram areas. The complex consists primarily of two regional thrust sheets vertically juxtapose a segment of the Tethyan oceanic crust. The lower nappe of the complex consists of Aptian-Albia pillow basalts that are overlain by Upper Cretaceous shale and chert. This thrust sheet has in turn been overthrust by a nappe containing serpentinized harzburgite, gabbroic/dioritic intrusives and sheeted dikes.

Deep marine sedimentary allochthons Deep marine sedimentary strata contained in regionally extensive allochthons and exposed in northern Waziristan and Kurram. These Cretaceous-aged strata were originally deposited above Tethyan oceanic crust, and later thrust on to the Indo-Pakistani continental margin following initial ophiolite emplacement. The siliciclastics, carbonates and cherts that make up this assemblage are subdivided into Stara Zakha, Spera Zhawar formations and the units of the Kurram Group.

Early Tertiary strata Strata of this assemblage include rocks that lie unconformably above the ophiolitic and deep marine nappes in western Waziristan. To the east and south, however, correlative strata are transitional with rocks of the Indo-Pakistani shelf sequence. The rocks of this unit are interpreted as being deposited in a flexurally and later transtensionally partitional foreland basin that developed during the initial collision of the Indo-Pakistani craton with Eurasia during Early Tertiary time (Beck et al., 1996). The siliciclastics, carbonates and evaporites that make up the early collision assemblage include the Datta Khel Formation, Lockhart Limestone, Patala Formation, Panoba/Ghazij Formation, Shekhan Formation, Jatta Gypsum, Mami Khel Formation, Kohat Limestone, Kirthar Formation and Spera Ghar Limestone.

Late Tertiary non-marine foreland basin strata Oligocene strata are mainly absent in the study area, although they can be found in the Katawaz basin and farther southward in the Lower Indus Basin. However, nonmarine Miocene – Holocene strata are widely exposed in the study area. These rocks including the Murree Formation, the Kamlial Formation and the Siwalik Group, were deposited across the study area as a result of initial and continued development of the present day fold and thrust belt. Due to the nonmarine origin, however, these foreland basin strata were not included in the biostratigraphic investigation presented below.

OBJECTIVES AND METHODS The biostratigraphy of the tectonostratigraphic units in the study area is poorly documented. As such, temporal trends in basin development, and the timing of the regional tectonic events are relatively unrefined. In order to provide more detailed age and paleoenvironmental control for the rocks of the region, detailed biostratigraphic analyses were conducted for the Mesozoic – Early Tertiary tectonostratigraphic units of Western Pakistan. The results of this investigation are presented here. Biostratigraphic samples were collected from key stratigraphic units in the Waziristan, Kurram, Zhob and Kohat areas. The lithology, sample number, and

geographic location were recorded for each sample and entered in to an electronic database to facilitate data management. Biostratigraphic samples were divided into two categories, soft samples such as marl and shale, and hard samples such as limestone, sandstone and chert. About 200 grams of soft sample were used to prepare slides of microfossils. The samples were treated with 25% hydrogen peroxide (H2O2) and a few drops of ammonia (NH4OH) to defloculate the samples. The deflocculated samples were washed through a 63µm sieve. Washed residues were treated in an ultrasonic bath for 5 minutes for further cleaning and dried afterwards in an oven at 80o C. Samples were then stored in properly labeled vials for the study. The microfossil residue was separated into four grain-size classes (>63µm, >125µm, >250µm, >630µm) for ease of handling. Approximately 300 specimens of foraminifers from each sample were examined under a binocular light microscope. Samples that could not be deflocculated were thin sectioned and studied directly under a polarized-light microscope. Laboratory results were reported in ASCII format and merged with the field sample database for GIS analysis and in comparison with geological data generated in previous studies.

Identification of Microfossils The planktonic foraminifers were identified following the species and zonal concepts of Caron (1985), Toumarkine and Luterbacher (1985), Blow (1979) and Berggren et al. (1993). The smaller benthic foraminifers were identified after Loeblich and Tappan (1988) and Jenkins and Murray (1989). The larger benthic foraminifers were identified after Davies (1937 b), Smout (1954) and Weiss (1988).

Zonal Scheme Several planktonic foraminiferal zonal schemes are currently in use for the Cretaceous and Tertiary (Premoli Silva and Bolli, 1973; Stanforth et al., 1975; Blow, 1979; Toumarkine and Luterbacher, 1985 and Berggren and Miller, 1988). Berggren and Norris (1993) revised their zonal scheme and redefined some of the early Paleocene zones. For the present study, a combination of these zonal schemes was generated that is based mainly on the association of larger benthic foraminifers and planktonic foraminifers found in the region (Fig. 2-4).

Chronobiostratigraphy Planktonic foraminiferal datum levels and faunal events for Cretaceous and Tertiary strata have been commonly used in correlating sedimentary sequences and building age models (Miller et al. 1987; Corefield, 1987; Park and Miller, 1992; Lu and Keller, 1993). The datum levels used in this study are zonal boundary marker foraminifera; the first occurrence and the last occurrence of significant species were considered secondarily. Chronological calibration of datum level and faunal events used in this study are based on the magnetostratigraphy of Bleil (1985). Sample (and therefore stratigraphic) ages were assigned based on characteristic zonal marker species and the first occurrence and the last occurrence of any diagnostic species found in the samples. All age assignments in this study have been adjusted to the time scale of Harland (1990) for consistency with previous work.

Figure 2-4: Zonal Correlation used in this study, (1) numerical ages, chrons and polarity are assigned (after Harland et al., 1990); (2) planktonic foraminiferal zonation scheme for Paleocene and Eocene by Berggren et. al., (1995) and for Cretaceous by Caron (1985); (3) larger benthic association scheme adopted after (Weiss, 1988); (4) Radiolaria zones assigned (after Sanfilippo and Riedel, 1985)

GENERALIZED LITHOSTRATIGRAPHY AND BIOSTRATIGRAPHY The stratigraphic succession exposed in the study area ranges in age from Triassic to Tertiary (Fig. 2-5). A detailed lithostratigraphic and biostratigraphic description of each of the tectonostratigraphic unit is presented below. The geographic localities from where the stratigraphic units were identified are shown in the figure 2-6.

Triassic-Cretaceous Indo-Pakistani shelf strata Upper Triassic to Cretaceous strata originally deposited on the Indo-Pakistani continental shelf has been documented from Eastern Waziristan, Kurram and Kohat areas (Fig.2-7). Stratigraphically this assemblage includes the Khan Kot Formation, Nimar Azrai Formation, Razani Formation, Zer Ghar Limestone, Zargaran Shale, Srapa Mela Formation, Samana Suk Formation, Chichali Formation, Lumshiwal Formation and Darsamand Limestone The age and depositional setting of these rocks were first described by Hemphill and Kidwai, (1973) and Meissner et al. (1975). These interpretations, however, have been revised based on the data presented below.

Triassic strata

Khan Kot Formation

Distribution and Lithology The oldest strata exposed in the Waziristan area of NW Pakistan are the rocks of the Triassic-aged Khan Kot Formation. These rocks are exposed in the metamorphosed footwall of the Waziristan Ophiolite and near Khan Kot in the South Waziristan Agency. Where associated with Waziristan Ophiolite, the formation consists of thinly- to medium- bedded, coarse- to fine-grained sandstone, calcilutite, oolitic calcarenite, black, gray, green, red and gray shale (Cassaigneau, 1979). In the less metamorphosed exposures of the formation near Khan Kot, the unit is dominated by gray and green shale, and contains interbeds of calcarenite and quartzose sandstone near its base.

Biostratigraphy and Age The Khan Kot Formation is barren of microfauna, but does contain small quantities of carbonized organic matter. This organic material has yielded rare (2-5 specimen per sample) palynomorphs such as: Sulcatisporites sp, Cycadopites sp, Falcisporites stabili, Psilasporites reteraformis, and Perinopollenites sp. Of these palynomorphs, both Falcisporites stabili and Psilasporites reteraformis are age diagnostic and indicate a Late Triassic- Early Jurassic age of deposition (Fowel and Traverse, 1995).

Figure 2-5: Composite stratigraphic column of Triassic to Eocene strata exposed in the study area.

Figure 2-6: Map showing prominent geographic and sample localities in the study area.

and Hemphill (Sources, strata margin passive to Cretaceous Triassic of map Outcrop 2-7: Figure Kidwai, (1975); Meissner et al., (1975) and present study)

Paleoenvironmental Interpretation

The presence of oolitic sandstone and palynomorphs in the Khan Kot Formation may suggest a near shore, shallow marine environment (Fowel and Traverse, 1995). As such, the Khan Kot Formation is interpreted as part of the Indian inner-shelf sequence, which may be equivalent to deep water strata described by Cassaigneau (1979) in eastern Afghanistan near Khost. However the presence of radiolarian beds in Afghanistan, farther west of the study area, indicate deeper water depositional conditions.

Comparison with Previous Work Based on the presence of radiolarite beds in Afghanistan area, the Khan Kot Formation was previously interpreted as deep marine/abyssal strata equivalent to the Middle Triassic to Upper Jurassic Khost Group (Beck, 1995). However, based on the presence of oolites and palynomorphs in the Waziristan area, this unit has been reinterpreted as being deposited in a shallow marine environment.

Jurassic strata Jurassic strata are widely exposed in the Waziristan, Kurram and Zhob areas. Stuart (1922) assigned these strata in the Waziristan area as Janjal Plant Series, which consist of Nimar Azrai Formation, Zer Ghar Limestone, Danawat Formation, Razani Formation, Srapa Mela Formation and Zargaran Shale. In the Kurram area, Jurassic strata consist of the Samana Suk Formation and Chichali Formation. In the Zhob area, the Jurassic consists of entirely of the Wazak Formation.

Nimar Azrai Formation Distribution and Lithology Light to dark gray shale intercalated with greenish limestone and thin beds of quartzose sandstone crops out at Nimar Azrai village in the eastern South Waziristan Agency along the Shinkai Toi area. Similar strata were found in the Dakai Area along the Ghorium-Dosali road in the North Waziristan Agency, and at Kot Langer Khel, along the Kaniguram-Razmak road in the South Waziristan Agency. The shales are hard and calcareous with fractures that are sometimes coated with iron oxide. Some burrows are visible along bedding planes. Primary sedimentary features such as ripple marks are present in the calcarenite. The stratigraphic position of the Nimar Azrai Formation places it in the lower part of Stuart’s (1922) Triassic-Jurassic Janjal Plant Series (Coulson, 1940).

Biostratigraphy and Age The Nimar Azrai Formation yielded palynomorphs and smaller benthic foraminifers of Early Jurassic age. The shale samples yielded carbonized dark brown to black color woody organic matter. A poor assemblage of palynomorphs was recorded. The palynoflora include: Inaperturopollenites sp; Classopollis simplex, Baltispharidium sp., Michystridium sp. ?Perinopollenites sp, Biretisporites ? modestus, Classopollis cf C.

chateaunovi, Psilasporites marcidus, Cyathidites minor, Cycadopites crassimarginatus, and ?Eisenackia sp . Samples from the shales of the Nimar Azrai Formation yielded smaller benthic foraminifera and ostracods. The foraminiferal assemblage identified from these samples consisted of Trocholina nodulosa, Trocholina nodulosa compressa, Dentalina intorta, Dentalina pseudocommunis, Ammodiscus siliceus, Eoguttulina cf. E. liassica, Glomospirella sp., Pseudonodosaria sp., Marginulina prima striata, Lingulina sp. Trochammina sp. and Ammobaculites sp. The presence of Eoguttulina cf. E. liassica bounds the upper time limit of the strata to the Lias stage of Early Jurassic while the other above-mentioned microfauna and microflora indicates the lower age limit of Late Triassic. Thus over all age of the strata is Late Triassic (Upper Triassic) - Early Jurassic (Lower Jurassic, Lias).

Paleoenvironmental Interpretation The dominance of palynomorphs, smaller benthic foraminifera, and ostracods, in conjunction with the preserved sedimentary structures, suggests a shallow shelf depositional environment for the Nimar Azrai Formation.

Comparison with Previous Work The Nimar Azrai Formation represents the lower part of Stuart’s (1922) Triassic- Jurassic Janjal Plant Series (Coulson, 1940) and based on the stratigraphic position, had been interpreted as being deposited in an outer shelf to slope environment (Beck, 1995). However the presence of palynoflora, and diagnostic smaller benthic foraminifers such as Trochammina and Ammobaculites indicate a shallow marine environment of deposition. As such, the Nimar Azrai Formation is interpreted as a part of the shelf sequence of the Indian craton.

Zer Ghar Limestone Distribution and Lithology The massive limestone forming Zer Ghar mountain 4 km east of Miram Shah Fort was named as the Zer Ghar Limestone by Smith (1895). The formation is >300 m thick at its type locality and ~900 m thick in the high ridge beneath Chinarop Piquet. Section of the formation exposed north of Chinarop Piquet and at Aziz Khel indicate that the Zer Ghar Limestone consists of, light brownish gray wackestone packstone, grainstone, and calcirudite (Beck, 1995). The wackestones and packstones are poorly sorted, bioclastic pelmicrites with irregular patches of micrite, spar and iron oxide. Grainstones are hard and moderately to well sorted, fine to coarse grained, bioclastic, intraclastic peloidsparites with smaller benthic foraminifera, rare ooids and very-coarse-sand to granule-sized intraclasts. Some grainstones are also oolitic, coarse- sand to granule-sized ooids that are set in a matrix of fine to medium, bioclastic peloidsparite. Bioclasts include mainly smaller benthic foraminifera, rare gastropods, echinoids spines/fragments, and pelecypods.

Biostratigraphy and Age Samples of the Zer Ghar Limestone yielded rare to moderate (2-15 per sample),

calcareous and agglutinated smaller benthic foraminifera. The foraminiferal assemblage included: Textularia sp., Ammobaculites sp., Lenticulina volubilis, Lenticulina subalta Dentalina intorta, Ammodiscus asper, Planularia protracta, Nodosaria sp., Legena sp., Marginulina sp. Of these foraminifera Lenticulina volubilis, Lenticulina subalta, Dentalina intorta, Ammodiscus asper, Planularia protracta are age diagnostic and suggest a Middle Jurassic age for the Zer Ghar Limestone.

Paleoenvironmental Interpretation The presence of Ammobaculites sp. is an indication of a shallow marine environment (Jenkins and Murray, 1989). Zer Ghar Limestone also contained oolites, which are characteristics of a shallow marine high-energy environment. However, since most of these shallow water indicators are encountered in beds deposited by sediment gravity flows (turbidites and subaqueous debris flows), the Zer Ghar Limestone was most likely deposited in an outer shelf to slope depositional environment.

Comparison with Previous Work Beck (1996) thought the Zer Ghar Limestone was deposited in middle to outer shelf environment. Given the Middle Jurassic age of the formation, the Zer Ghar Limestone may be the deep-water equivalent of the shallow marine Samana Suk Formation in the Kohat and Kurram areas.

Danawat Formation Distribution and Lithology Shales of the Danawat Formation are exposed near the intersection of the Danawat Algad and the Jandola-Tani Post road in Southern Waziristan Agency. Coulson (1940) referred to these strata as rocks of the Danawat Stage. The thickness of the Danawat Formation is estimated to be ~1500 meter (Beck, 1995). The Danawat Formation is comprised primarily of green, light gray to greenish gray, moderately hard, splintery shale. The formation also contains sheared horizons of thin-bedded calcilutite/micrite, and black, olive gray to greenish gray, soft to moderately hard, silty shale.

Biostratigraphy and Age The shale of Danawat Formation contains smaller benthic foraminifera, radiolaria, dinoflagellates and palynomorphs. Samples from the Danawat Formation yielded the following microfauna and microflora. Smaller benthic foraminifera were common (16-50 per sample) in the samples. These included: Nodosaria opalina, Trocholina nodulosa, Planularia angustissima, Dentalina intorta Frondicularia cf. F. sulcata, Nodosaria sp., Dainitella explanata, Nodosaria issleri Garantella rudia, Epistomina sp., Paazowella fiefeli regularis, Frondicularia intermittens, Nodosaria globulata, Nodosaria sp., Lenticulina exgr. muensteri, Litunella sp., Dentalina pseudocommunis, Haplophragmoides infracalloviensis, Trocholina nodulosa, Ammodiscus siliceous, Trochammina sp., Glomospirella spp. and Verneuilinoides sp. Danawat Formation samples also contained rare radiolaria such as Mirifusus

mediodilatus, Sethocapsa cetia and Croleonium pythiae. Fine grained organic matter extracted from the Danawat Formation samples yielded the following palynological assemblage: Inaperturopollenites sp., Cicatricosisporites potomaensis, Gleicheniidites senonicus Podocarpidites sp., Paleoperidinium ? cretaceum, Ovoidinium sp., Nannoceratopsis pellucida, Zonalapallenites sp., ?Acanthaulax acanthosphera, Meiuorogonyaulax strongylos, Concavsporites juriensis, Biretisporites sp., Veryhacium valensi, Subtilispheara sp., Gonyaulacysta sp., Trilobosporites sp., Tenua sp., Preodinia ceatophora, P. cracenta, Leptodinium sp., Sentusidinium rioulti, Cleistosphearidium sp., Chlamydopharella wallala, ?Tubotuberella sp., Broomea simplex, Prolixosphearidium truncispinum, P. mixtispinum, Oligosphearidum pulcherrimum, Pareodinia sp., Canningia sp., Sentusidinium pilosum, Sirmiodiniopsis ? apiapertus and Dingodinium cf D. alberti. Of the observed microfossils, only the smaller benthic foraminiferal assemblage is age diagnostic. The presence of Dentalina pseudocommunis, Haplophragmoides infracalloviensis, Trocholina nodulosa and Ammodiscus siliceous indicates Middle to Late Jurassic age for the Danawat Formation.

Paleoenvironmental Interpretation The presence of radiolaria and dinoflagellates suggests a low energy outer shelf to slope depositional environment for the Danawat Formation. Pollens in the formation may be reworked.

Comparison with Previous Work Coulson (1940) correlated the limestone beds present in the Danawat Formation with the Zer Ghar Limestone, the Bobai Limestone and the Sulaiman Limestone. However, since shale is the dominant lithology in the Danawat Formation it is more likely that the Danawat Formation is correlative to the shale rich Chichali Formation in the Samana range. The Danawat Formation as a whole has been interpreted as deep marine strata originally deposited out board of the Indian shelf sequence (Beck, 1996).

Razani Formation Distribution and Lithology At Alexandra Ridge Fort along the northeast margin of the Razmak Valley, in the western North Waziristan Agency, a 10-meter thick bed of calcarenite and calcirudite has been classified as Razani Formation (Beck, 1995). In this section, the Razani Formation forms the resistant cap of the ridge (Razmak Manza) and slope. Petrographic analyses indicate that the associated packstone is a poorly sorted, coarse to very coarse, bioclastic intramicrite with a few ooids (oncoids?). A thick section of gray shale, brown sandstone and oolitic calcarenite/calcirudite crops out north of Alexandra Post in the North Waziristan near the village of Alexandra Ridge along the Razmak-Dosali Road. At this locality, the Razani Formation is a few hundred meters thick and consists of medium- to fine-grained brown sandstone interbedded with black to green shales. Sandstone beds are 1-2 m thick near the base of the section, are relatively thin in the middle of the section and then thicken from 1 to 40 cm in the upper part of the section.

The base of the Razani Formation is a brownish gray to grayish brown, packstone and grainstone. The packestone is well-sorted medium to coarse bioclastic oomicrite with granules and pebble-sized intraclasts. The grainstone is moderately to well sorted, coarse oolitic (oncolitic?), bioclastic intrasparite. The top of the formation is light gray to greenish gray, hard, faintly laminated shale.

Biostratigraphy and Age The shale samples of the Razani Formation contain rare benthic foraminifera, while limestone samples contain a moderate occurrence of smaller benthic foraminifera, which included Parurgonina Caelinensis, Textularia sp. Ammodiscus siliceous, Trocholina nodulosa and Haplophragmium sp. The presence of Parurgonina Caelinensis species at all levels in the formation suggests Late Jurassic (Oxfordian to Kimmeridgian) age for the Razani Formation.

Paleoenvironmental Interpretation Based on the abundant oolitic/intraclastic packstone and grainstone, and the presence of smaller benthic foraminifera such as Parurgonina Caelinensis, Haplophragmium sp. and Textularia sp., the Razani Formation is interpreted as being deposited in a shallow marine environment.

Comparison with Previous Work Stuart (1922) assigned a Jurassic age to Razani Formation and on the basis of lithologic similarities he placed it into Janjal Plant Series. Lithologically the Razani Formation is similar to the Sulaiman Formation in the Mughal Kot area (Stuart, 1922) and therefore it is considered as a part of Indian Shelf sequence.

Srapa Mela Formation Distribution and Lithology Shales exposed near Srapa Mela between Miram Shah and Spinwarm in North Waziristan are classified as the Srapa Mela Formation (Beck, 1995). The Srapa Mela Formation consists of brick red to light brown, friable to soft, calcareous shale.

Biostratigraphy and Age Srapa Mela Formation yielded smaller benthic foraminifera such as: Ammmodiscus siliceous, Ammobaculites agglutinaus, Lenticulina tricarinella Dentalina intorta, and Trochammina sp. Of this smaller benthic assemblage, Ammobaculites agglutinaus, Lenticulina tricarinella and Dentalina intorta are age diagnostic and indicate a Late Jurassic age for the Srapa Mela Formation.

Paleoenvironmental Interpretation Based on the smaller benthic agglutinated foraminiferal assemblage of Trochammina sp. and Ammobaculites agglutinus, a shallow marine depositional environment is assigned for the Srapa Mela Formation (Murray, 1988).

Comparison with Previous Work The Srapa Mela Formation was interpreted by Beck (1995) as an allochthonous unit originally deposited in a middle to outer shelf environment. However the presence of smaller benthic foraminifera suggests the formation was deposited in a shallow marine setting.

Zargaran Shale Distribution and Lithology The Zargaran Shale is exposed in a series of synforms above the Razani Formation along the Khaisora River in the North Waziristan District (Beck, 1995). The basal contact is exposed one km SSE of the village of Zargaran, on the south side of a tributary of the Khaisora River. Similar strata crop out in a synform near Karama village ~15 km to the south where unit is a minimum of 700 meters thick. Its lithology, belemnites and stratigraphic position suggest that the Zargaran Shales are equivalent to the Upper Jurassic/Lower Cretaceous Sperkai, Chichali and Sembar formations in areas to the south. The Zargaran Shale consists of interbedded shale and thinly bedded limestone. The shale is light gray to greenish gray, hard, and faintly laminated. The limestone is a dark gray, hard mudstone with medium silt size quartz and elongated dolomitic/phosphatic (?) burrows.

Biostratigraphy and Age Zargaran Shale is barren of microfauna or microflora but contains rare belemnites. Although lacking age-diagnostic fossils, an Upper Jurassic-Lower Cretaceous age has been assigned to the Zargaran Shale on the basis of its stratigraphic position (Beck, 1995). Paleoenvironmental Interpretation With an absence of microfauna and microflora in the unit, it is difficult to interpret the paleoenvironmental setting of Zargaran Shale. However, based on the stratigraphic position of the formation it is interpreted that Zargaran shale was deposited in a shallow marine environment (Beck, 1995).

Samana Suk Formation Distribution and Lithology In the Kurram area there is widely exposed oolitic unit known as Samana Suk Formation (Shah, 1977). The limestone is thick on northern and eastern sides in the Kohat Potwar area, but pinches out westward and southwards in central Spingwar, north of Parachinar (Badshah et al., 2000). In the type locality, the Samana Suk Formation is gray to dark gray, medium to thick-bedded limestone with subordinate marl and calcareous shale intercalations. The limestone is oolitic and has some shelly beds. In the Surgar Range, the limestone is lighter in color, medium to thin-bedded and marly and shaly in the lower part. In the Kohat and Tribal areas the Samana Suk Formation is a thick-bedded, dolomitic and ferruginous, sandy, oolitic limestone (Shah, 1977).

Biostratigraphy and Age Samana Suk Formation yielded only indeterminate smaller benthic foraminifers. Fatmi (1968, 1972) described brachiopods, gastropods, ammonoids and crinoids in the Samana Suk Formation. The characteristic ammonoid species are Reineckeia ancepts, Choffatia cobra, Obtusicostites buckmani, Hubertoceras sp and Kinkeliniceras sp. Based on the characteristic ammonoid species Fatmi (1972) assigned a Middle-Late Jurassic age of the Samana Suk Formation. Paleoenvironmental Interpretation The Samana Suk Formation contains abundant oolites and shelly beds, which suggests deposition in a shallow marine, high-energy environment.

Comparison with Previous Work Calkins, 1968, Latif, 1970 a and Fatmi, 1972 studied Samana Suk Formation in the Northern Hazara and Kala Chitta Range and found macrofauna, but there is no foraminiferal record for this formation. Based on the lithological similarities, Samana Suk Formation has been correlated to the Chiltan Limestone and Mazar Drik Formation in the lower Indus basin (Shah, 1977). Based on the sedimentary petrography, the oolites and onkolites are the common feature present in the study area during Jurassic time, which indicates that Zer Ghar Limestone, Danawat Formation and Razani Formation in the Waziristan are the facies equivalent of Samana Suk Formation.

Cretaceous strata Cretaceous-aged shelf strata in the Northern Waziristan, Kurram, Kohat and Zhob areas consist of the Chichali Formation, Nai Kach/Nili Kach/Sembar Formation, Chorai Nallah/ Goru Formation and Darsamand Limestone.

Chichali Formation Distribution and Lithology The Chichali Formation is the name assigned to the black belemnite-bearing shales present below the Parh Limestone in the Borai Tangi area. These strata are equivalent to the Sembar, Shini Naria, Karama and Chichali formations of the Kurram and Kohat areas. In the west of Bannu, the formation consists of dark green, greenish gray, thinly laminated micritic shales with belemnites. Near the Gomal Pass, west of the Nili Kach WAPDA camp, it is mainly comprised of black glauconitic shales with belemnites. Organic rich and coal bearing beds are present in the formation in the Kohat area.

Biostratigraphy and Age Shale samples of the Chichali Formation from Thal Hangu valley contained commonly occurring (16-50 per sample) smaller benthonic foraminifera. The characteristic agglutinated foraminifera recovered from the formation are Haplophragmoides infracalloviensis Recurvoides sublustris Haplophragmoides sp. Verneuilinoides spp.and Ammobaculites sp.

Of these, Haplophragmoides infracalloviensis and Recurvoides sublustris are age diagnostic and indicate a Middle Jurassic (Bathonian) age of deposition. However, based on ammonoids fauna, the depositional age of the formation in Kohat area extends into the Early Cretaceous (Shah, 1977). As such it appears that the Chichali Formation was deposited from the Middle Jurassic to the Early Cretaceous. Paleoenvironmental Interpretation The presence of Haplophragmoides infracalloviensis Recurvoides sublustris Haplophragmoides sp. Verneuilinoides spp. Ammobaculites sp places the Chichali Formation in a shallow marine environment. In addition, the coal bearing beds reflect the presence of deltaic environments in the Kohat area.

Comparison with Previous Work In the eastern Kohat, Nizampur, Kala Chitta and Hazara, the basal beds of the Chichali Formation contain late Oxfordian to early Neocomian macrofauna. Based on these fauna the age of the Chichali Formation has been interpreted as Late Jurassic to Early Cretaceous (Shah, 1977). Early Cretaceous microfauna were also observed in samples from the Kohat area (Shafique, 1993). The Chichali Formation represents a long depositional age and variable environment from shallow marine to deltaic in nature.

Nai Kach Formation Distribution and Lithology Strata of the Nai Kach Formation crop out in the central part of Waziristan and in the southern Kurram Agency. Coulson (1940) named these strata as the Nai Kach Stage. The Nai Kach Formation consists of black belemnite bearing micritic shale with interbedded black siltstone and nodular, reddish- weathering, argillaceous limestone. Glauconite is commonly present which gives the greenish hue to the weathering color. Locally the basal part of the unit contains pyritic nodules. Lithologically Nili Kach and Sembar formations are correlative to the Nai Kach Formation.

Biostratigraphy and Age The black shales of the Nai Kach Formation yielded rare smaller benthic foraminifera such as Glomospira sp., Haplophragmoides cf. H. walteri, Saccammina aff. S. sphaerica, Spiroplectamina sp., Astoculus sp., Lenticulina muenstri, Ammodiscus sp. and Gavelinella barremiana. Rare occurrences of radiolaria were observed in these strata. Identifiable radiolarian species were recovered from the formation include: Sethocapsa trachyostraca and Sethocapsa uterculus. The species present are frequently observed as reworked grains in the Tertiary strata of the region. As such, the Sembar/Nai Kach Formation may be the source of the reworked radiolaria found in the younger rocks. Sampled lithologies also yielded abundant organic matter that contained the following palynomorphs: Baltisphearidium sp., Biretiporites sp., Chlamydophorella sp., Classopollis classoides, Ephedripites sp.?, Eucomiidites?, Foraminisporites sp., Gingkocycadophytus nitidus, Gleicheniidites senonicus, Inaperturopollenites sp., Leiotriletes sp., Monocolpites sp., Odontochitina operculata, Pareodinia ceratophora, Podocarpidites ellipticus, Sphagnites clavus, Spiniferites spp., Spiriferites hypercanthus, Spiriferites lenzi, Spiriferites multibrevis, Trisaccites sp., Veryhachium sp.,and

Zonalapollenites dampieri The presence of Sethocapsa trachyostraca and Sethocapsa uterculus radiolarian species indicate an Early Cretaceous depositional age for the Nai Kach/Nili Kach Formation/ Sembar Formation.

Paleoenvironmental interpretation The presence of radiolaria suggests a low energy outer shelf. However the palynomorphs present in the samples suggest the region was close enough to the coastline for the abundant microflora assemblage to accumulate.

Comparison with Previous Work Stuart (1922) identified abundant Lower Cretaceous belemnites in the Nai Kach Formation and similar types have been identified in the Sembar Formation in southern Waziristan and the Mughal Kot area. These species were assigned upper Neocomian ages by Stuart (1922). Fatmi (1968, 1972) identified a Late Jurassic ammonoid from the Sembar Formation of Lower Indus Basin extending the lower age of Sembar Formation to Late Jurassic. As such the Nai Kach and Nili Kach formations may also be as old as Late Jurassic. The Late Jurassic to Early Cretaceous age of the Nai Kach Formation suggests it is correlative to the similar-aged Chichali Formation in Kohat (Shah, 1977).

Chorai Nallah/Goru Formation Distribution and Lithology In Waziristan, the Chorai Nallha Formation overlies the Nai Kach Formation. The type section is located at Chorai Nallah in eastern Waziristan approximately 3 km north of the Tochi River, and less than 1 km west of the prominent Spina Ghora ridge (Meissner et al., 1975; Hemphill and Kidwai, 1973). The Chorai Nallah Formation consists of interbedded belemnite bearing limestone, shale and siltstone. The limestones in the formation are thin bedded, light to medium gray-olive gray micrite/calcilutites. The interbedded shale and siltstones are gray, greenish gray and locally maroon in color. The Chorai Nallah Formation is a correlative of the Goru Formation, which is exposed in the Southern Waziristan and Zhob areas.

Biostratigraphy and Age Microfossils in the Chorai Nallah Formation consist of rare occurrences of planktonic and smaller benthic foraminifera. Observed planktonic foraminifera includes Ticinella roberti, Ticinella madecassiana, Hedbergella sp. and Praeglobobtruncana delrioensis. Smaller Benthic foraminifera from the formation include Ammodiscus cretaceous, Glomospira sp., Trochammia sp, and. Gavelinella cf. G.intermedia The presence of the planktonic foraminifera Ticinella roberti and Ticinella madecassiana species indicate an Early Cretaceous (Albian) age for Chorai Nallah/Goru Formation.

Paleoenvironmental Interpretation The presence of planktonic foraminifera is indicative of a low energy, open marine environment. This faunal assemblage is different from the shallow water

indicators observed in the underlying Chichali/Sembar formations. As such, the Chorai Nallah/Goru Formation may have deposited in a deep-water setting following a marine transgression that occurred across the region during Early Cretaceous time.

Comparison with Previous Work Fritz and Khan (1967) and Shafique and von Daniels (1990) interpreted a similar planktonic foraminiferal assemblage in the Goru Formation of the Kirthar range as being deposited in an open and deep marine environment.

Darsamand Limestone Distribution and Lithology Limestone above the Lumshiwal Formation and Chichali Formation in southern Kurram and Kohat has been classified as the Darsamand Limestone. The Darsamand Limestone at its type section is a lithographic to sub lithographic, gray, olive gray and light gray, micrite/mudstone with subordinate shale and marl.

Biostratigraphy and Age The Darsamand Limestone is richly fossiliferous and yielded both planktonic and smaller benthic foraminifers. The planktonic foraminifers are, however, the dominant microfossils in the unit. The following benthic foraminiferal assemblage was observed from samples from the Darsamand Limestone: Praebulimina carseyae, Nodosria spp. and Gavelinella spp. Planktonic foraminifera observed in the unit include: Globotruncana lapparenti, Globotruncana linneiana, Globotruncana mariei, Globotruncana oriantalis, Globotruncanita stuartiformis and Heterohelix spp. All the Globotruncana species observed in the unit, are age diagnostic and indicate a Santonian – Campanian (Late Cretaceous) depositional age. Paleoenvironmental Interpretation The abundant planktonic foraminifera in the Darsamand Limestone indicate an open marine-outer shelf depositional environment. Comparison with Previous Work Fatmi (1972) and Latif (1970) identified planktonic foraminifers from the Darsamand Limestone in samples collected from the Kala-Chitta and Hazara areas. On the basis of these fossils they assigned the unit to the Coniacian to Campanian stages of Upper Cretaceous. However in Kurram and Kohat area, no Coniacian microfauna were recovered. As such, the Darsamand Limestone in the study area may be younger than similar strata in adjacent regions.

Waziristan Ophiolite Complex The location of ophiolitic rocks in Waziristan, Kurram and eastern Afghanistan are shown in figure 2-8 a & b. The Waziristan Ophiolite Complex consists of two regional thrust nappes that contain distinct lithologic assemblages. The lower nappe consists of pillow and sheet-flow basalts that are overlain by the Campanian Barazi Chert and Zhizha Olistostromes (Badsha et al., 2000; this study). The upper nappe consists of a metamorphic sole comprised of blueschist facies amphibolites that is overlain by an ophiolitic sequence. The ophiolitic rocks include a serpentinized harzburgite mantle

sequence (Jones, 1960; Jan et al., 1985) that is overlain by gabbros and sheeted-dykes. The sheeted dykes are in turn overlain by pillow and sheet-flow basalts and red-gray pelagic radiolarian chert and limestone (Gnos et. al., 1997). Post emplacement granitoid dikes locally cut the basaltic extrusives.

Allochthonous Deep Water Strata Allochthonous deep marine strata in the study area are made up of the Stara Zakha, Spera Zhawar and Haidri Kach formations and the Kurram (Hemphill & Kidwai, 1975; Beck, 1995; Gnos, 1997). These units are exposed in the northern Waziristan, Khost and western Kurram Agency (Fig. 2-9). The stratigraphic age of the deep water allochthons has, in the past, been poorly defined with estimates ranging from Triassic to Cretaceous (Kaever, 1967a; Hemphill & Kidwai, 1973; Badshah et al., 2000). The new biostratigraphic data presented below, however, indicates these strata are Cretaceous – Paleocene in age. The oldest strata in the allochthons were deposited above pillow lavas during Aptian-Albian time while the youngest strata were deposited synchronus with ophiolite obduction during the Campanian and Maastrichtian. As such, these rocks record the deeper depositional transition from passive margin, outer shelf/slope/rise setting, to flexurally partitioned marine foredeep. These deep-water rocks were then under thrust by the dismembered ophiolites and emplaced on to the Indian continental margin during Maastrichtian to Paleocene time (Beck, 1995).

Stara Zakha Formation Distribution and Lithology Green shale of Stara Zakha Formation crops out in the North Waziristan Agency west of the Mir Ali-Thal road at Stara Zakha, NW of Spinwam. The greenish shale is soft, friable and splintery. The strata are allochthonous and show intense deformation (Beck, 1996) . Biostratigraphy and Age Microfossils in the Stara Zakha Formation consist of commonly occurring smaller benthic foraminifera and radiolaria. Smaller benthic foraminifera observed in the unit include Glomospira gordialis, Glomospira variabilis, Glomospira serpeus, Glomospira gaultina, Ammodiscus planus, Trochammina sp., Praecystammina globigerinaeformis, Bathysiphon sp., and Textularia sp. Radiolaria identified from the formation consist of Holocryptocanium barbui, Crystamphorella conara, Theocorys antiqua and Pseudodictyomitra sp. Of these microfossils Holocryptocanium barbui, Crystamphorella conara and Theocorys antiqua are age diagnostic species and indicate an Aptian – Albian (Lower Cretaceous) age of deposition.

Figure 2-8 a: Outcrop of Waziristan and Khost ophiolites (after Robinson, 2000 Gnos, 1998).

Figure 2-8b: Detailed outcrop map of Waziristan Ophiolites (inset Fig. 2-8a).

igure 2-9: Outcrop map of deep marine Middle to Late Cretaceous allochthonous units (after Gnos, F 1998 and present study).

Paleoenvironmental Interpretation

Siliceous smaller benthic foraminiferal species such as Glomospira gordialis and Ammodiscus planus indicate deep marine deposition. The presence of common radiolaria and agglutinated smaller benthic foraminifers indicate deposition below the carbonate compensation depth (CCD).

Comparison with Previous Work Beck (1996) considered the Stara Zakha Formation as being deposited in an open marine shelf environment. However the presence of radiolaria and characteristic siliceous smaller benthic foraminifers such as Glomospira spp. suggests a deep marine environment probably below the calcium carbonate compensation depth (CCD). Given the allochthonous nature of unit, the Stara Zakha Formation may have been deposited directly above oceanic crust represented by adjacent ophiolite sequences.

Spera Zhawar Formation Distribution and Lithology The Spera Zhawar Formation is exposed at Spera Zhwar Algad in the Shahur Tangi gorge, South Waziristan Agency. It consists of olive to greenish gray, friable, hard, laminated and nodular shale. Biostratigraphy and Age The Spera Zhawar contains abundant radiolaria and smaller benthic foraminifera. The smaller benthic foraminifera include Glomospirella gaultina, Paratrochamminoides sp., and Glomospira gordialis. These species suggest a Cretaceous age of deposition.

Paleoenvironmental Interpretation The abundance of radiolaria and deep water benthic foraminifera such as Glomospirella gaultina, Paratrochamminoides sp. and Glomospira gordialis suggest a deep marine depositional setting for the Spera Zhawar Formation. Because of its age and paleogeographic setting, these strata are interpreted as the parautochthonous record of the ophiolite obduction (Beck, 1995).

Kurram Group Distribution and Lithology The Kurram Group is contained in an extensive structural nappe overlying ophiolitic and the Indian shelf strata exposed in the west of Waziristan and Kurram areas (Hemphil & Kidwai, 1973). The following formations are included in the Kurram Group: the Kahi melange, the Shinki Post/Kurram Formation and the Khajuri Post Formation. In general, the Kurram group consists of interbedded greenish gray to white limestone and purple chert. Petrographic analyses indicate that the limestone consists of foraminiferal-radiolarian packstone/wackestones and laminated mudstone. Radiolarian wackestones/packstone also contain some peloids. Allochems include abundant chalcedony-filled radiolarians, few smaller benthic foraminifera and other bioclasts. Limestone also contain irregularly distributed iron carbonate that has been altered to iron

oxide and calcite filled fractures and veins. The chert is a laminated, brecciated, silicified mudstone with some radiolarians. Pillow lavas with red inter-pillow sediments are present at several localities within the group.

Biostratigraphy and Age Overall, the Kurram Group yielded planktonic foraminifera, deep water smaller benthic foraminifera and radiolaria. Based on the characteristic microfauna association the age of the Kurram Group ranges from Santonian to Maastrichtian (Late Cretaceous).

Kahi melange Distribution and Lithology The Kahi melange of southern Kurram is a mixture of limestone, chert, ophiolitic rocks, volcaniclastics and older deformed clastic sediments (Beck, 1995 a). The intensity of deformation within these rocks increases from south to north. The Kahi melange is equivalent to the Saidkaram melange of eastern Afghanistan (Beck, 1996) and has been thrust southward and eastward at least 50 km over the Paleocene strata of Lockhart Limestone (Davies, 1926; Meissner et al., 1975; Beck et al., 1995a). Petrographic analyses indicate Kahi limestones are greenish gray, laminated, planktonic foraminiferal packstones. Shale in the Kahi Melange shows a variety of colors such as green, red and purple and is intensely deformed. The shale is interbedded with quartzose sandstone, calcirudite, calcarenite, cleaved calcisiltite and calcilutite. Blocks of chert in the Kahi Melange range from few meters to hundreds of meters in diameter. Smaller blocks often occur as clasts in rudites while the larger blocks are of cream to white colored radiolarian chert. The chert varies from relatively pure silica to silicified mudstone containing some radiolaria.

Biostratigraphy and Age The following foraminiferal assemblage was frequently observed from samples of the Kahi Melange: Globotruncana ventricosa, Globotruncana cf. G. calcarata, Heterohelix sp., Globotruncana bulloides, G. linneiana,G. lapparenti, G. orientalis. Hedbergella spp., Praeglobotruncana spp. Helvetoglobotruncana helvetica, Praeglobotruncana stephani Whiteinella brittonensis and Marginotruncana sp. Heterohelix navarroensis Globotruncana arca, G. egyptica, Heterohelix globosa, Pseudogumbilina costulata A few smaller benthic foraminifers such as Textularia sp., Gavelinella sp., Recurvoides sp. Saccammina placenta, Harmosina aff. H. ovuloides , Haplophragmoides cf. H. concavus ,Ammodisceus sp., Osangularia cordieriana Reussella szajnochae szajnochae, Pseudouvigerina cristata, Glomospira aff. G. gordialis Ammodiscus cretaceus Haplophragmoides sp, .? Globorotalia micheliniana, Saccammina spp were also recovered from the unit In addition the radiolaria Thanarlas ? veneta, Cryptamphorella conara and Pseudoaulophacus floresensis were also identified from the Kahi melange. The planktonic foraminiferal assemblage of H. Helvetica, Globotruncana ventricosa, Globotruncana cf. G. calcarata and G. aegyptiaca indicate a Turonian- Middle Maastrichtian age of deposition for the strata of the Kahi melange.

Paleoenvironmental Interpretation The carbonates and shales of the Kahi melange contain abundant Globotruncanids, suggesting they may have been deposited as calcareous oozes and pelagic muds in a deep, fully open marine depositional environment. The rocks of the Kahi melange contain abundant Turonian, Campanian and Maastrichtian microfossils. It is important to note that the Santonian microfauna are missing from the Kahi Melange, except for a few Santonian-Campanian radiolarians recovered from volcaniclastic samples. The lack of abundant Santonian microfossils from these rocks, however may not be indicative of a depositional hiatus. Globally, there appears to be a mass extinction of microfauna during the Santonian (Eldholm, 1990). This extinction has been correlated with high levels of CO2 in both the atmosphere and ocean (Eldholm, 1990).

Shinki Post Formation Distribution and Lithology The Shinki Post Formation crop out west of Shinki Post along the bank of the Tochi River in the northern Waziristan Agency. The Shinki Post Formation consists of reddish brown shale, calcirudite, calcarenite, calcilutite and minor quartzose sandstone. Shales of the formation are light brown to reddish in color, soft and calcareous. Limestone beds of the Shinki Post Formation consist of calcilutite, calcarenite and calcirudite. Petrographic analyses of the coarse-grained limestones indicate they are grainstones that contain fine to very coarse, bioclastic, peloidal, oolitic intrasparite with some granule to pebble size intraclasts, coral fragments, echinoid fragments, planktonic foraminifera, and smaller benthic foraminifera. Sparse fine glauconite is also present, and a few samples are partially silicified. Bedding characteristics and sedimentary structures indicate turbidity currents deposited coarse-grained lithologies.

Biostratigraphy and Age The Shinki Post Formation contains abundant planktonic foraminifera, nannofossils and rare smaller benthic foraminifera. The following planktonic foraminiferal assemblage was observed from samples of this unit: Heterohelix sp, Globotruncana spp., Rugoglobigerina sp., Heterohelix globosa Archeoglobigerina blowi, Globotruncana laperenti, Gta. linneiana, Globotruncanita stuartiformis, Gta. ventricosa, Gta. Bulloides, Pseudotextularia elegans, and G. falsostuarti. A few smaller benthic foraminifers such as Bolivina sp., Textularia sp., Nodosaria sp. were also recovered from this unit. Nannofossils, interpreted as the remains of single celled calcareous algae were also observed in the Shinki Post Formation. The representative nannofossils assemblages are: Watanaureria barnesae, Stradneria crenulata, Micula staurophora, Quadrum gartneri, W. biporta, W comunis, Predicosphaera cretacea and Eiffellithus sp. Of the microfossils identified from the Shinki Post Formation, the planktonic foraminiferal assemblage of Globotruncanita stuartiformis, Gta. ventricosa, Gta. Bulloides, Pseudotextularia elegans, and G. falsostuarti indicate a latest Campanian age of deposition. In addition to the Campanian planktonic foraminifera, there are abundant broken shells of reworked Late Cretaceous fossils in the coarse-grained lithologies of the Shinki

Post Formation. The presence of these reworked fossils suggest that during the Campanian parts of the basin were undergoing significant tectonic related deformation and erosion (Beck, 1996).

Paleoenvironmental Interpretation Based on the abundance of planktonic foraminifera and nannofossils, the Shinki Post Formation is interpreted as the deposits of a low energy, deep, open, marine depositional environment. However the presence of oolitic, peloidal, intraclastic, bioclastic and glauconitic limestone indicates this overall pelagic system experienced episodic turbiditic deposition. The Shinki Post Formation and the overlying Khajuri Post Formation (see below) were grouped with the radiolarite-bearing rocks of the Kahi Mélange on the basis of hydrodynamic and paleoenvironmental information (Beck et al., 1995). However outcrop relationships and observed microfauna indicate the Shinki Post Formation and Khajuri Post Formation are parautochthonous Upper Campanian strata. As described in the following chapter, Mughal Kot strata in the Mughal Kot Gorge indicate a ~74 Ma age of ophiolite emplacement. This age is similar to the Campanian depositional age of the Shinki Post Formation. Based on this age similarity, and the evidence of significant intrabasinal tectonism during deposition, the Shinki Post is interpreted to represent synobduction sedimentation in the Waziristan region

Khajuri Post Formation Distribution and Lithology Limestone and reddish brown sandstone of the Khajuri Post Formation crops out along the Shahur Tangi gorge, in the Khaurai Ghora in Waziristan and to the west of Thal Fort. The unit is also exposed in southern Kurram and the Thal-Hangu valley where it is intensely deformed as part of the Kahi Melange (Beck, 1996). The Khajuri Post Formation is mainly yellowish brown, friable to moderately hard, slightly calcareous sandstone and limestone. Petrographic analyses indicate that the sandstone is a fine to very coarse grained, sub angular to rounded, poorly sorted, texturally submature quartzarenite. Limestones of the formation are brownish gray, planktonic foraminiferal wackestones that contain fine-grained glauconite and elongated sand-to granule-sized chert nodules. Biostratigraphy and Age A moderate to common occurrence of planktonic foraminifera, smaller benthic foraminifera, and radiolaria were observed in samples from the Khajuri Post Formation. Planktonic foraminifera from the unit include: Heterohelix navarroensis, Globotruncana linneiana, Globotruncana angulata, Globotruncana aff. G. arca, G. bulloides and G. oriantalis. A smaller benthic foraminiferal assemblage consisting of Bolivinoides miliaris, Legina sp., Reussella szajnochae szajnochae, Pseudovigerina cristata, Bolivina incrassata, Praebulimina laevis, ? Quinqueloculina sp. Epinoides beisseli, Pullina sp., Gavelinella spp. and Bolivina sp. was also identified. Radiolarians recovered from the formation include: Cryptamphorella aff. C. conara, Dictyomitra aff. D. koslovae and Cryptamphorella conara The presence of Heterohelix navarroensis, Globotruncana linneiana, Globotruncana angulata and Globotruncana aff. G. arca suggest a Maastrichtian age of

the Khajuri Post Formation. Paleoenvironmental Interpretation The Khajuri Post Formation is rich in planktonic foraminifers, which indicate a deep marine depositional environment. The presence of planktonic foraminifers in association with radiolaria suggests an outer shelf to slope environment. Sandstones in the formation represent the deposits of turbidites in the deep marine environment. The microfossils preserved in the Khajuri Post Formation provide a new maximum age for the timing of deformation and emplacement of the deep-water allochthons. The open marine strata of the Khajuri Post Formation contain foraminifera diagnostic of the Early - Middle Maastrichtian Globotruncana aegyptiaca foraminiferal biozone (~74 Ma, based on Harland et al., 1990). In addition the uppermost Khajuri Post strata in the Tochi Gorge area also contain foraminifera of the latest Maastrichtian Abathomphalus mayaroensis biozone (Chapter 4). As such, emplacement of the allochthonous deepwater depositional units must have occurred after latest Maastrichtian time.

Early Tertiary Strata Following ophiolite and deep water allochthon emplacement Paleocene to Eocene sediments strata were deposited unconformably above the thrust terrains in Waziristan and Kurram and above Mesozoic shelf sequence in Kohat (Fig. 2-10). During this time, deposition in the region occurred in a flexurally and later transtensionally partitioned foreland basin produced as a result of the initial collision of India and Eurasia.

Paleocene strata The distribution of Paleocene strata varies across the study area. In Waziristan, the Paleocene consists only of the Datta Khel Formation. However in Kurram, Paleocene rocks include the Patala Formation, Chale Talao Formation and lower Ghazij Formation.

Datta Khel Formation Distribution and Lithology The Datta Khel Formation is a conglomerate made up of clasts derived from the underlying ophiolite complex and the Kurram Group. The unit unconforambly overlies the ophiolitic complex and the Kurram Group and is itself unconformably overlain by the Ghazij Formation and Spera Ghar Conglomerate. This unit represents the first strata deposited following ophiolite emplacement. The Datta Khel Formation is dark green to brown, red conglomerate, which contains ophiolitic clasts, set in a sandstone/siltstone matrix. Stratigraphically this unit is equivalent to the Hangu Formation exposed in the Kohat area.

Figure 2-10: Outcrop map of Lower Tertiary strata (after Hemphill and Kidwai, 1974; Meissner et al., 1975; Gnos et al., 1998 and present study).

Biostratigraphy And Age

The Datta Khel Formation yielded a sparse microfauna, consisting entirely of the smaller benthic foraminifera. Such as smaller rotaliids, Textularia spp. and Haplophragmoides spp. Although these foraminifera are not age diagnostic, the position of the Datta Khel Formation between the Maastrichtian ophiolite complex and the Early Eocene Ghazij Formation indicates a possible latest Maastrichtian – Paleocene age of deposition.

Paleoenvironmental Interpretation Based on the lithologic characteristics of the conglomerates and the presence of the smaller benthic foraminifera, the Datta Khel Formation is interpreted as being deposited in a high energy, shallow marine depositional environment. The Datta Khel Formation represents the basal deposits of a syntectonic basin developed above previously obducted ophiolite and deep water allochthons in western Waziristan during the initial collision of India and Asia (Badsha et al., 2000). Based on the lithologic characteristics and stratigraphic similarities, the Datta Khel Formation may be equivalent to the Baraul Banda Formation in the Kohistan area. As such, the maximum age of the Baraul Banda Formation may also provide a maximum age for the initiation of India-Asia collision in what is now the NW Himalaya. Currently, Baraul Banda Formation is undated. However preliminary biostratigraphic studies on the Baraul Banda Formation and overlying strata indicate a possible Late Paleocene age of deposition (Sullivan et. al., 1995). If this age is correct then the timing of initial continent-continent collision along the entire western margin may have been synchronous.

Lockhart Limestone Distribution and Lithology The Lockhart Limestone forms the top of the Paleozoic-Mesozoic-Cenozoic Indian shelf sequence in the Kohat and Kurram areas. The unit is a shallow marine limestone that contains abundant larger benthic foraminifera. The Lockhart Limestone is brownish gray to cream colored, medium to thick bedded, and rubbly to brecciated in places. Petrographic analyses indicate the limestones are grainstones that contain granule to pebble-sized intraclasts, bioclasts, oncoids and ooids.

Biostratigraphy and Age Abundant benthic foraminifera were observed in samples of the Lockhart Limestone. Observed larger benthic foraminifera include: Miscellanea miscella, Rotalia trochidifomis, Lockhartia haimai, L. conica, Operculina patalensis, O. jiwani, O. salsa, Redmodina henningtoni and Discocyclina ranikotensis. A smaller benthic foraminiferal assemblage was also observed that consisted of Cibicides lobatulus, Cibicides alleni, Cribogloborotalia challinori, and Anomalina spp The larger foraminiferal assemblage of Miscellanea miscella, Rotalia trochidifomis, Lockhartia haimai indicates Middle - Late Paleocene age for the Lockhart

Limestone.

Paleoenvironmental Interpretation Lithologic characteristics of the Lockhart Limestone and the presence of larger and smaller benthic foraminifers suggest the unit was deposited in a high-energy, shallow marine environment.

Comparison with Previous Work Meissner et al. (1974 & 1975), Wells (1984) and Pivinik (1992) studied lithofacies relationships of the Lockhart Limestone and interpreted the unit as being deposited in a Paleocene shallow marine environment prior to the collision between India and Asia. The Lockhart Limestone and overlying shale deposits of Patala Formation (see below) are Middle to Late Paleocene units that represent shallow marine deposition. These strata have been interpreted to represent a Paleocene-Eocene foreland basin (Wells, 1984; Yeats and Hussain, 1987) . The marine shale-rich facies is capped by a complex association of shallow water facies, which lack a marked asymmetry in their isopachs (Meissner et al., 1974; 1975: Wells, 1984; Pivnik, 1991)

Patala Formation/Chale Talao Formation Distribution and Lithology In the Northeast part of the Kohat Plateau, limestones, shales and sandstones of the Patala Formation gradationally overlie the Lockhart Limestone. Biostratigraphic data from the oil wells in Tolanj, Kahi and Sumari indicate an early Paleocene age for the base of the Patala Formation (Shafique, N. A., 1993). The base of this interval contains numerous limestone beds whose foraminiferal biostratigraphy suggests a rapid deepening during deposition. Overlying the basal Patala limestones are bathyal marine shales. The intense to moderate degree of deformation of rocks makes determination of the original thickness of the Patala Formation in the study area difficult. Sections of the Patala Formation at Samana Suk and Uch Bazzar (Meissner et al., 1976) contain a major thrust fault system referred to by Pivnik (1992) as the Main Boundary Thrust (MBT). The Patala Formation consists primarily of marine shale with thin beds of limestone and mudstone. The shale is dark greenish gray in color and, in places carbonaceous. The limestones are gray in color and highly fossiliferous. Petrographic analyses of the limestone indicate they are foraminiferal packstones and wackestones.

Biostratigraphy and Age A common occurrence of larger benthic, smaller benthic and planktonic foraminifera were observed in samples from the Patala Formation. The larger benthic foraminiferal assemblage observed from this unit include: Lockhartia haimei, Lockhartia hunti, Rotalia trochidiformis, Nummulites globulus, Ranikothalia bermudezi, Ranikothalia nuttali, Discocyclina ranikotensis, Operculina salsa, Operculina subsalsa, Miscellanea miscella, Dictyokathina simplex, Alveolina sp., Assilina daviesi, A.umbilicata, A. spinosa, Nummulites globulus, and Rotalia trochidiformis. The smaller benthic foraminiferal assemblage observed from the unit consist of: Cibicides lobatulus, Marssonella oxycona, Quinqueloculina pseudovata, Q.ranikotensis,

Pseudogloborotalia ranikotensis, Anomialina dorrri, Wooddella nammalensis, Cibicides alleni, Virgulina dubia, Aammodiscus sp and Glomospira sp. The upper part of the Patala Formation is rich in planktonic foraminifera. The following planktonic foraminiferal assemblage was observed from samples of this unit; Morozovella aequa, Morozovella quetra, M. albeari, M. acuta, M. subbotinae, Muricoglobigerina esnehensis, Mg. soldadoensis soldadoensis, Mg. soldadoensis angulosa, A. wilcoxensis wilcoxensis, A. wilcoxensis strabocella, A. mckannai, Subbotina linaperta, S. hornibrooki, Turbortalia psudoimitata, Acarinina lodoensis, Pseudohastigerina wilcoxensis, Mg. Aequiensis, Morozovella velascoensis velascoensis, M. angulata, M. velascoensis parva and M. acuta. Of these planktonic foraminifera the assemblage of Morozovella velascoensis velascoensis, M. subbotinae, Mg. soldadoensis soldadoensis and A. wilcoxensis wilcoxensis indicate a Late Paleocene to Early Eocene age of deposition (planktonic foraminifer zones P5 to P7).

Paleoenvironmental Interpretation The basal part of the Patala Formation is interpreted as shallow marine; while the top is deep marine. There was an abrupt change in basin setting of the region during the Late Paleocene to Early Eocene time as deep marine bathyal deposits of Patala Formation overlay the shallow marine strata of the Lockhart Limestone. This abrupt deepening in the Kohat Plateau region during the latest Paleocene has been interpreted as a result of flexural subsidence due to thrust loading during the initial stages of the Indo-Asian collision (Yeats and Hussain, 1987; Beck et al., 1995). Therefore the maximum age of the Patala Formation records the collapse of the flexural fore bulge (upon which the Lockhart Limestone may have been deposited) and the migration of the foredeep into the study area (e.g. DeCelles and Giles, 1996).

Comparison with Previous Work Previous work on the Patala Formation concentrated on exposures of the unit southeast of the Kohat Plateau in the Salt Range. From this area, Smout and Haque (1956) recorded larger benthic foraminifera while Haque (1956) reported smaller foraminifera. Latif (1970) reported planktonic and smaller benthic foraminifers from the Hazara areas. Raza (1967) and Cheema (1968) also recorded larger foraminifers from the Salt Range area and, interpreted the age of the Patala Formation as Late Paleocene. Afzal and von Daniel (1991) reported planktonic, smaller benthic and larger benthic foraminifers from the Namal Gorge section in the Salt Range and assigned an age of Late Paleocene to Early Eocene. The present study also suggests a Late Paleocene to Early Eocene age of the Patala Formation in the Kurram and Waziristan areas. However, the biostratigraphic analyses of well cuttings from Tolanj well, Kohat area, indicate, the base of the Patala Formation may be as old as Early Paleocene (Shafique, 1993).

Eocene Strata Eocene strata are widely exposed in NW Pakistan. In Kurram the Eocene is comprised of Panoba Shale, Shekhan Limestone, Jatta Gypsum, Mami Khel Formation

and Kohat Limestone. In the Zhob and Waziristan areas, Eocene rocks consists of the Ghazij Formation, Kirthar Formation and Spera Ghar Limestone

Panoba/Ghazij Formations Distribution and Lithology The Panoba and Ghazij formations are the oldest Eocene rocks in the study area. In Kurram, the Panoba Formation is transitional with the underlying Patala Formation. In the western and northern parts of Kurram, the unit is overlain by nonmarine strata of the Mami Khel Formation (Wells, 1984). To the south and east, the Panoba Formation grades upward into shallow water limestones and evaporites of the Shekhan Limestone, Bahadur Khel Salt and Jatta Gypsum (Meissner et al., 1974, 1975; Pivnik and Sercombe, 1993). The Panoba Formation consists of abundant shales with minor limestone, sandstone, and conglomerate. Shales of the formation are greenish gray to light gray in color, slightly silty, and calcareous near the base of the unit. Panoba limestones are mainly gray wackestones and packstones and contain allochems consisting of planktonic foraminfera, rare benthic foraminifera and echinoid fragments. A few samples contain rare fine-grained glauconite and irregularly distributed iron oxide. The Panoba Formation also contains siliciclastic sandstones and conglomerates (Pivnik, 1993) Although these siliciclastics were not described in detail as part of this study, reported contact relationships and internal sedimentary structures indicate they were deposited by sediment gravity flow (Beck, 1996). In Waziristan, the Ghazij Formation is the stratigraphic equivalent of the Panoba Formation. The Ghazij Formation consists of shale, limestone, sandstone and conglomerate lithologies that are similar to the Panoba Formation.

Biostratigraphy and Age Samples from the Panoba/Ghazij Formation yielded rare larger benthic foraminifera and abundant planktonic foraminifera. In addition, the upper part of the Panoba Formation also yielded reworked Jurassic palynomorphs and Cretaceous radiolaria. Panoba/Ghazij sandstones yielded rare Tertiary larger benthic foraminifera that had been slightly reworked. The assemblage identified from these samples consisted of Nummulites spp., Assilina laminose, Discocyclina spp., Miscellanea miscella and Assilina daviesi. However these species were subsidery to the abundant planktonic foraminifera observed from shales and limestones of the formation. The following planktonic foraminiferal assemblage was observed from samples of this unit; Morozovella formosa formosa, M. quetra, M. subbotinae gracilis, M. aequa aequa, Acarinina wilcoxensis wilcoxensis, A. wilcoxensis strabocella, Planorotalites pseudoscitula, Acarinina aff. A. nicoli, Muricoglobigerina soldadoensis soldadoensis, Morozovella subbotinae subbotinae, Subbotina aff. S. linaperta, Planorotalites chapmani Of the planktonic species, the presence of Morozovella formosa formosa species is age diagnostic and indicates an Early Eocene age of deposition for the Panoba and Ghazij formations.

Paleoenvironmental Interpretation Based on the presence of abundant planktonic foraminifera, the Panoba/Ghazij Formation is interpreted as being deposited in an open marine environment. The shale dominated character of the unit and the presence of possible turbiditic sandstones and conglomerates suggests that part of the unit was deposited in a deep marine setting. However, the upward transition into nonmarine and evaporitic strata overlying the Panoba and Ghazij formations may indicate the upper parts of the formations were deposited in progressively shallower water through time.

Comparison with Previous Work The Panoba and Ghazij formations have been interpreted as being deposited in a regional transtensional basin that developed along the northwest margin of the Indian continent following initial collision with Asia (Beck, 1995; Beck et al 1995). The presence of reworked Jurassic palynomorphs and Cretaceous radiolaria in Panoba and Ghazij formations suggests that this basin was bounded by highlands containing uplifted Mesozoic rocks of the Indian shelf sequence. Proprietary palynologic studies indicate that the Eocene palynomorphs are rare compared to the abundance of the recycled Jurassic palynomorphs. This suggests that there was limited weathering and rapid deposition of sediments transported into the basin during the Early Eocene.

Shekhan Limestone Distribution and Lithology The Shekhan Limestone represents the base of a general eastward and southward thinning and shallowing observed in Eocene strata above the Panoba Formation in the Kohat Plateau. The Shekhan Limestone is several tens of meters thick in the Northwestern part of the Kohat Plateau but thin to only a few meters in the northeastern part of the region. In its type section at Shekhan Nallah, the Shekhan Limestone contains abundant benthic foraminifera and shallow water mollusks (Pivnik, 1993). The western most exposure of the Shekhan Limestone is exposed at Ibrahimzai village (Khwaja Khazar) on the Kohat-Hangu Road (Pivnik, 1992; Pivnik and Sercombe, 1993). The Shekhan Limestone consists of interbedded limestone and shale. The limestone is yellowish gray to gray to light brown, thin bedded to massive and nodular. Petrographic analyses of the limestones indicate that they are moderately sorted foraminiferal wackestone and packstone with finely crystalline dolomite patches. Shales of the unit are gypsiferous.

Biostratigraphy and Age The samples from the Shekhan Limestone contain commonly occurring larger and smaller benthic foraminifera. The following larger benthic foraminiferal assemblage was observed from samples of this unit: Assilina laminose, A. spinosa, A. daviesi, A. leymerie, Nummulites globules, N. vredenburgi, Alveolina elliptica and Nummulites atacicus The smaller benthic foraminifera observed in the Shekhan samples consist primarily of Miliolid types. Individual species, however, were not identified due to poor preservation. Based on the larger benthic foraminifera Nummulites globulus, A. daviesi and Nummulites atacicus, a late Early Eocene is assigned to the Shekhan Limestone.

Paleoenvironmental Interpretation The presence of larger benthic foraminifera indicates a high-energy, shallow marine environment of deposition, while the presence of Miliolid indicate ocean water circulation may have been somewhat restricted.

Comparison with Previous Work Nagappa (1959) and Pascoe (1963) reported Early Eocene larger benthic foraminifera from the Shekhan Limestone. Based on the foraminifera identified in the present study, the depositional age of the Shekhan Limestone is further constrained to the late Early Eocene.

Jatta Gypsum Distribution and Lithology Evaporites of the Jatta Gypsum and Bahadur Khel Salt crop out in the southern and north-central portions of the Kohat Plateau (Meissner et al., 1974, 1975; Wells, 1984). These evaporites interfinger with the Panoba Formation to the north and west and strongly control the location and orientation of surface fold and faults in the area (Mc Dougall and Farrah, 1990; Pivnik and Sercombe, 1993). The Jatta Gypsum is greenish white in color, massive and hard. Thin partings of red, purple and green clay occur at different intervals with in the unit (Shah, 1977). The maximum thickness observed in the Para Chinar area is about 70 meters (Meissner et al., 1974).

Biostratigraphy and Age Samples of the Jatta Gypsum were barren of microfauna but the stratigraphic position of the unit indicates it is Early Eocene in age.

Paleoenvironmental Interpretation As indicated by the gypsum, deposition of the Jatta Gypsum most likely occurred in a shallow highly restricted marine environment. This restricted setting may have developed due to continued structural segmentation of the basin associated with transform deformation along the northwest margin of the Indian craton.

Comparison with Previous Work The Jatta Gypsum is correlative to the Baska Shale and the Albaster Member of the Ghazij Formation in the Sulaiman Range. The Jatta Gypsum represents a phase of uplift that isolated the Kohat basin from the adjacent areas and resulted in a restricted marine condition favorable for the development of evaporites.

Mami Khel Formation Distribution and Lithology The Mami Khel Formation represents the transition from marine to terrestrial deposition across the region. Near its type section at the village of Mami Khel, the formation contains marine shale, limestone and sandstone. To the north and west

however, the formation includes nonmarine shale, sandstone and coarse conglomerate. The conglomeratic facies is particularly well developed near Kundi Village. Marine lithologies of the Mami Khel Formation consist of brownish red-to-red soft silty calcareous shale and thin beds of mottled purple sandstone and brownish-cream colored limestone. Petrographic analyses indicate the limestones are wackestones that contain sparse benthic and planktonic foraminifera. Nonmarine shale contains fossils of blue green algae.

Biostratigraphy and Age Samples of the Mami Khel Formation yielded a rare occurrence of larger benthic foraminifera including Assilina laminosa, Discocyclina sp., and Nummulites sp. The presence of Assilina laminosa indicates an Early Eocene depositional age for this unit.

Paleoenvironmental Interpretation Based on the presence of larger benthic foraminifers a shallow marine depositional environment is interpreted for the marine part of the Mami Khel Formation. However the nonmarine strata contained in the formation indicate that the Mami Khel Formation was deposited during an overall phase of regression during the later part of the Early Eocene.

Comparison with Previous Work Meissner et al. (1974) found sporadic smaller benthic foraminifers in the Mami Khel Formation and assigned an Early Eocene age.

Kohat Limestone Distribution and Lithology Early to Middle Eocene shallow marine strata in Kurram and northern Kohat Plateau have been classified as Kohat Limestone. The Kohat Limestone consists of dominantly carbonate lithologies but also contains some interbedded shale. The Kohat limestones are yellowish brown to cream white wackestones, packstones and grainstones that contain intraclasts, ooids, foraminifera and other bioclasts. Some samples also contained glauconite and quartz grains. As a whole, the Kohat Limestone forms resistant ridges and is an important marker bed for structural and stratigraphic mapping in the study area (Meissner et al., 1974; Meissner et al., 1975).

Biostratigraphy and Age Kohat Limestone samples contain abundant larger foraminifera and a moderate occurrence of smaller benthic foraminifera and rare planktonic foraminifera. The observed larger benthic foraminiferal assemblage includes Nummulites atacicus, N. globulus, Alveolina sp., Nummulites atacicus, N. globulus, Rotalia trochidiformis, Alveolina sp. Nummulites sp. Alveolina oblonga Alveolina elliptica, Orbitolites complanatus and Dictyoconus sp. The observed smaller benthic foraminiferal assemblage consisted of Textularia sp., Cibicides spp., smaller Rotaliids, Anomalina midwayensis, Robulus sp. Miliolids,

Nodosaria sp., Textularia sp. and Quinqueloculina sp. Only one planktonic foraminifera, Subbotina sp,. was identified. Based on the presence of the larger benthic foraminifera Nummulites globulus and Orbitolites complanatus a Late Early to Middle Eocene age is interpreted for the Kohat Limestone.

Paleoenvironmental Interpretation The presence of larger benthic foraminifers in abundance suggests a shallow, high-energy marine depositional environment for the Kohat Limestone. Limestones and shales of the Kohat Limestone indicate a return of fully marine deposition during late Early and early Middle Eocene time. This episode of marine deposition may have been due to a global rise of sea-level (Hallam, 1992).

Comparison with Previous Work Eames (1952) and Meissner et al. (1968) reported mollusks and larger benthic foraminifers from the Kohat Limestone and assigned Early to Middle Eocene age. The results of the current study are compatible with this age.

Kirthar Formation/ Spera Ghar Limestone Distribution and Lithology In the southwest Kohat Plateau, and along the western margin of the Indus foreland, late Early – Middle Eocene strata have been classified as the Kirthar Formation. In Waziristan, the same stratigraphic interval has been termed the Spera Ghar Limestone. In general, both the Kirthar and Spera Ghar are equivalent to the lower Kohat Formation in the northern Kohat Plateau. Where exposed along the western margin of the Indus Foreland, the Kirthar Formation is subdivided into four members. In ascending order these members are the Habib Rahi Member, Domanda Shale Member, the Pir Koh Limestone Member, and the Drazinda Shale Member. The following is a brief description of each member: Habib Rahi Member: grayish brown, thin to thick-bedded limestone and coquina; Domanda Member: dark brown to greenish gray claystone; Pirkoh Member: brown gray to white limestone with subordinate argillaceous limestone; Drazinda Member: brown to gray shale with subordinate marl and sandstone. In the southern part of the study area, the Kirthar Formation is overlain by a low- angle unconformity cuts down section towards the north, towards Gomal Pass, removing the upper three members of the formation (Hemphill and Kidwai, 1973). Because of this, north of Gomal Pass, Kirthar Formation nomenclature is not used (Meissner et al., 1975).

Biostratigraphy and Age The Kirthar Formation/Spera Ghar Limestone is richly fossiliferous and contains abundant larger benthic foraminifera. The following larger benthic foraminiferal assemblage was observed from samples of these units: Assilina exponensis, Assilina stylocoenia, Nummulites atacicus, Nummulites vredenburgi, Alveolina elliptica, Orbitolites complanatus, Dictyoconus indicus, Discocyclina sp., Assilina laminose, and Lockhartia hunti.

Based on the presence of Nummulites atacicus and Orbitolites complanatus a late Early to Middle Eocene age is assigned to the Kirthar Formation/Spera Ghar Limestone.

Paleoenvironmental Interpretation The presence of abundant larger benthic foraminifera suggests a shallow water, high-energy marine environment of deposition. Regional deposition of Kirthar equivalent shallow marine strata above the deformed belt and foreland indicates a relatively low rate of subsidence within the basin during late Early – Middle Eocene time. This may have been caused by a decrease in the rate of tectonic loading during this time.

Comparison with Previous Work Early Oligocene fauna were reported from the Kirthar Formation south of the study area in the Kirthar Range (Hunting Survey, Corporation, 1961). However, no microfauna younger than Middle Eocene were observed in the present study. Therefore an upper age of Middle Eocene is interpreted for these limestones. SUMMARY OF BIOSTRATIGRAPHIC ZONES Based on the above biostratigraphic analyses, a time stratigraphic correlation of each tectonostratigraphic interval has been developed (Fig. 2-11). Structural complexity and inaccessibility due to political problems in the region prevented the routine and systematic sampling of rocks in the study area. Most samples within a known section are random and do not represent the true tops or bottoms of a stratigraphic unit. Similarly the sample interval is approximate, which prevents the accurate determination of zonal continuity within a given sequence. However study results identified a relatively continuous zonation from the Late Paleocene to Early Eocene (P5 – P9) characterized by the persistence of the marker fauna or assemblages the delineate partial range zones. Despite these difficulties the extensive biostratigraphic work resulted in the following biozonation of the study area:

Jurassic Strata Lias Stage

Eoguttulina liassica, Ammodiscus siliceous, Trocholina nodulosa Association A few samples in the Nimar Azrai Formation yielded the smaller benthic foraminiferal species Trocholina nodulosa, Ammodiscus siliceous, Eoguttulina liassica and Dentalina pseudocommunis (Fig.2-12), which are characteristic of the Lias stage of the Early Jurassic. Therefore the Nimar Azrai Formation is placed in the Lias stage and in the Eoguttulina liassica, Trocholina nodulosa and Ammodiscus siliceous association.

Bajocian-Callovian Stage

Lenticulina subalta, Lenticulina vobulus and Planularia protracta Association The smaller benthic foraminifera Lenticulina subalta, Lenticulina vobulus and Planularia protracta, were identified from the base of the Zer Ghar Limestone. This

assemblage is characteristic of the Bajocian-Callovian stage of the Middle Jurassic. As such the base of the Zer Ghar Limestone is assigned to the Lenticulina subalta, Lenticulina vobulus and Planularia protracta association of this stage

Oxfordian-Kimmeridgian Stage

Parurgonina caelinensis zone The smaller benthic foraminifera Parurgonina caelinensis is a characteristic species of the Oxfordian and Kimmeridgian stages of the Late Jurassic (Allemann, 1979). This species was frequently identified in samples from the upper part of Danawat Formation and in the Razani Formation (Fig.2-12). As such the top of Danawat Formation and the Razani Formation falls within the Parurgonina caelinensis zone.

Cretaceous Strata

Barremian Stage

Gavelinella barremiana Zone The smaller benthic foraminifera Gavelinella barremiana was identified in the Nai Kach Formation in the Waziristan area. This species is a representative of the Barremian stage of Early Cretaceous (Fig.2-13) and the Nai Kach Formation is therefore placed in the Gavelinella barremiana zone.

Albian Stage

Rotalipora appenninica Zone The first appearance of the planktonic foraminiferal species Ticinella roberti, Ticinella madecassiana, Hedbergella sp. and Praeglobotruncana delrioensis occur in the Chorai Nallah Formation. Based on the last occurrence of Ticinella roberti and the first occurrence of Praeglobotruncana delrioensis the Chorai Nallah Formation is assigned to the Rotalipora appenninica zone of the Albian stage (Fig. 2-13).

Turonian Stage

Helvetoglobotrucana helvetica Zone The planktonic foraminifera Praeglobotruncana stephni, Whiteinella brittonensis, Marginotruncana sp. and Helvetoglobotruncana helvetica were identified in samples of from the lower part of the Kahi Melange. Of these, Helvetoglobotruncana helvetica is a zonal index fossil of Turonian (Caron, 1985). Therefore the oldest identified strata from the Kahi melange fall with in the Helvetoglobotruncana helvetica zone (Fig. 2-13).

Figure 2-11: Time stratigraphic correlation of sedimentary tectonostratigraphic units of the study area.

Figure 2-12: Foraminiferal Distribution of Jurassic strata identified in Waziristan and Kurram areas. Numerical ages are assigned (after Harland et al., 1990).

Santonian Stage

Dicarinell asymetrica Zone It is interesting that no Santonian microfauna were identified from the Kahi Melange. However a few Santonian species were found in one of the olistolith samples from the Spera Zawar Formation including the planktonic foraminifera Dicarinella concavata, Dicarinella asymmetrica, and Globotruncana ventricosa and other Globotruncanids. As such this sample can be placed in the Santonian stage Dicarinella asymetrica zone (Caron, 1985) (Fig. 2-13).

Campanian Stage

Globotruncana calcarata Zone The Shinki Post and Khajuri Post formations and the Kahi Melange (Fig. 2-13, 2- 14) are richly fossiliferous and yielded a number of planktonic foraminiferal species such as Heterohelix sp, Globotruncana spp., Rugoglobigerina sp., Heterohelix globosa Archeoglobigerina blowi, Globotruncana laperenti, Gta. linneiana, Globotruncanita stuartiformis, Gta. ventricosa, Gta. Bulloides, Pseudotextularia elegans, and G. falsostuarti. Based on the first and last occurrences of the characteristic species, the entire Shinki Post Formation, the lower part of Khajuri Post Formation, and the middle part of the Kahi Melange are counted in the Campanian Stage, Globotruncana calcarata zone.

Maastrichtian Stage

Globotruncana aegyptiaca Zone A continuous zonation from Late Campanian to the Early Maastrichtian is present in the upper Khajuri Post Formation and upper Kahi Melange. The following planktonic foraminiferal assemblage was found in these strata: Heterohelix navarroensis, Globotruncana linneiana, Globotruncana angulata, Globotruncana aff. G. arca, G. bulloides and G. oriantalis Globotruncana bulloides, Heterohelix spp. and Globotruncana aegyptiaca species. Based on the species Globotruncana aegyptiaca, these strata fall with in the Early Maastrichtian Globotruncana aegyptiaca zone (Fig.2- 14)

Paleocene Strata

Thanetian Stage

Planorotalites pseudomenardii P4 Zone A number of samples from the Lockhart Limestone and Patala Formation yielded a planktonic foraminiferal assemblage in association with larger benthic foraminifers

Figure 2-13: Foraminiferal Distribution of Cretaceous strata studied in the Waziristan and Kurram areas. Numerical ages are assigned (after Harland et al., 1990).

such as Ranikothalia nuttali, Lockhartia hamei and Miscellanea miscella. Based on the frequent occurrence of Planorotalies pseudomenardii and the last occurrence of Morozovella angulata the top of Lockhart Limestone and the base of Patala Formation all fall with in the Late Paleocene Planorotalites pseudomenardii zone (Fig.2-15) (Bolli, 1985).

Morozovella velascoensis P5 Zone Samples from the middle part of the Patala Formation contained a planktonic foraminiferal assemblage consisting of Subbotina triangularis, Subbotina linaperta, Morozovella velascoensis, Morozovella aequa, Morozovella acuta, Muricoglobigerina esnehensis and Acarinina wilcoxensis. The presences of marker the species, Morozovella velascoensis, indicate the middle part of the Patala Formation lies with in Morozovella velascoensis zone (Bolli, 1985) of the Late Paleocene.

Eocene Strata Ypresian Stage

Morozovella edgari P6 Zone The upper part of the Patala Formation yielded planktonic foraminifera such as Morozovella aequa, Morozovella edgari, Morozovella marginodentata and Subbotina sp. (Fig.2-15). Based on the presence of Morozovella edgari, a zonal marker, the upper part of the Patala Formation falls with in the Early Eocene Morozovella edgari zone (Bolli, 1985).

Morozovella subbotinae P7 Zone The base of the Panoba Shale is characterized by the presence of the following planktonic foraminiferal species; Acarinina wilcoxensis, Morozovella subbotinae, Morozovella aequa, Morozovella quetra, Acarinina nicoli and Muricoglobigerina soldadoensis. This assemblage represents Morozovella subbotinae partial range zone (P7).

umerical ages are assigned (after Harland et al., 1990). igure 2-14: Foraminiferal Distribution of Cretaceous Kahi Melange strata studied in the Kurram and Thal areas. F N

Figure 2-15: Foraminiferal Distribution of Paleocene strata studied in the Waziristan and Kurram areas. K.K.O.M = Kahi Kurram Orakzai Melange and K.M. = Kahi Melange. Numerical ages are assigned (after Harland et al., 1990).

Morozovella formosa P8 Zone

Based on the presence of the characteristic zonal species, Morozovella formosa, in few samples from the Panoba Shale, Morozovella formosa zone is assigned for these particular samples of the Panoba Shale (Fig.2-16). Acarinina pentacamerata P9 Zone The planktonic foraminifera species Acarinina pentacamerata, Acarinina broadermani, Muricoglobigerina soldadoensis, Subbotina inaequispira, Acarinina interposita, Acarinina pseudotopilensis and Turborotalia griffinai were identified from the upper part of the Panoba Shale. Based on these species, the upper Panoba Shale is assigned to the Early Eocene Acarinina pentacamerata partial range zone (Bolli, 1985).

Nummulites globulus Association Larger benthic foraminifera are abundant in the upper most part of the Panoba Shale, the Shekhan Limestone and the lower part of the Kohat Limestone. One characteristic Early Eocene species, Nummulites globulus was present in many of the samples from these formations. As such, these strata have been assigned to the Early Eocene.

Flosculina globosa Association The upper part of the Kohat Limestone and the Spera Ghar Limestone yielded larger benthic foraminifera including the characteristic Middle Eocene species Flosculina globosa. For this reason, the upper Kohat and Spera Ghar Limestone are assigned to the Floscolina globosa association (Fig.2-17).

TECTONIC CONTRLS ON BASIN DEVELOPMENT The biostratigraphic and paleoenvironmental data presented above has allowed a more accurate reconstruction of the tectonic controls on Mesozoic – Cenozoic deposition in NW Pakistan. Mesozoic deposition across the region began with a period of Early Triassic rifting followed by passive margin development (Fig. 2-18). Environmentally diagnostic microfauna identified in the rocks of each tectonostratigraphic unit are described below. Interpreted changes in paleoenvironmental setting between stratigraphic units were used to identify fluctuations in relative sea level through time. These changes are controlled by various tectonic processes, which are displayed in Figures 2-18 to 2-20. In Triassic time the breakup of Gondwana resulted in marine sedimentation as far south as the central Indus basin (Hunting, 1960). Shallow to open marine conditions with deepening to the west is recorded along the western margin from Triassic to Middle Jurassic time (Fig. 2-21). Smaller benthic foraminiferal species such as Eoguttulina liassicaAmmodiscus siliceous and Dentalina intorta were identified in the Early Jurassic Nimar Azrai Formation. These species represent shallow environment, therefore Early Jurassic is interpreted as the shallow marine shelf depositional environment. Dentalina intorta, a smaller benthic foraminiferal species is continuously present in the Zer Ghar Limestone and represent shallow marine environment in the Middle Jurassic time. There is a change of

Figure 2-16: Foraminiferal Distribution of Early Eocene identified in Waziristan and Kurram areas. Numerical ages are assigned (after Harland et al., 1990).

Figure 2-17: Foraminiferal Distribution of Early to Middle Eocene strata studied in the Waziristan and Kurram areas. Numerical ages are assigned (after Harland et al., 1990).

Figure 2-18: Depositional history of the Indo-Pakistani passive margin strata exposed in Waziristan and Kurram, deduced from the characteristic foraminiferal, radiolarian assemblages and palynomorphs observed in the study area.

environment at the end of Middle Jurassic at the time deposition of Danawat Formation as indicated by Lenticulina tricarinella and other smaller benthic association, which represent relatively deeper water environment. The presence of Parurgonina caelinensis, in the Upper Jurassic Danawat Formation and Razani Formation indicate a shallow marine deposition, which is supported by the presence of oolites in these formations. As such, the Upper Jurassic stratigraphic interval is interpreted as being deposited in an inner shelf depositional setting. There is a change in the depositional environment in the Early Cretaceous resulting an open marine shale deposition over the region as a transgressive facies. The shales of Nai Kach, Haidri Kach and Chorai Nallah formations contain abundant smaller benthic foraminifera that include Lenticulina spp. and Nodosaria spp. The presence of these species indicates a deep-water environment in the Early Cretaceous as compared to the Late Jurassic. The Early Cretaceous interval is interpreted as being deposited in an outer shelf – slope setting. The transition from passive to active margin in Pakistan began with the initiation of ophiolite obduction during Campanian time (~ 74 Ma). A flexurally subsiding foreland basin, which developed in response to tectonic loading accompanying obduction, filled with sediment derived from the Indian craton as well as the uplifted ophiolites and ophiolitic melange (Fig. 2-22). Siliciclastic sediment shed from the ophiolitic mélange was deposited until at least the Middle Maastrichtian (Globotruncana aegyptiaca zone). Frequent keeled Globotruncanids were observed in the Upper Cretaceous strata, which indicate open marine deposition from Turonian to Maastrichtian time. However, the presence of abundant Radiolaria, Cryptamphorella conara and Pseudoaulophacus floresensis at different horizons reflects relative increase in water depth during deposition of the Stara Zakha and Spera Zhawar formation (Fig. 2-19). The shales of Shinki Post Formation contain abundant planktonic foraminifera and smaller benthic foraminifera. Over all, the planktonic to benthic foraminiferal ratio in the formation is more than one, indicating an open marine depositional environment. However the presence of reworked oolitic limestone beds and characteristic shallow water smaller benthic foraminifera such as the Milliolids, Haplophragmoides spp. and Trochammina sp. indicate an influx of shallow water sediments from shelf into deep marine foredeep during this time. The presence of ophiolitic mélange and olistostromes unconformable beneath the Upper Paleocene (P5) Patala Formation, ≥100 km SE of the NW Indian Plate margin implies thrusting and/or gravitational emplacement of ultramafic blocks and radiolarites a great distance onto the northwestern Indian continental margin before the end of the Paleocene. Indeed, a nearly identical early Paleocene to upper middle Eocene scenario has been documented in detail (Bruggey et al., 1973b; Cassaigneau, 1979; Kaever, 1967) at Khost in eastern Afghanistan, where syntectonic lower to middle Paleocene conglomerates contain upper Cretaceous clasts. In the Hazara syntaxis of northern Pakistan, latest Paleocene to earliest Eocene P6-P7 tidal sandstones contain chrome-spinels thought to be derived from the Kohistan segment of the Trans-Himalayan Arc and suggest pre-Eocene collision of India with the Trans-Himalayan Arcs (Bossart and Ottiger, 1989). The Kohistan Arc Complex was accreted to Eurasia before the end of the Campanian in northern Pakistan (Petterson,

Figure 2-19: Depositional history of allochthonous strata exposed in the study area, deduced from the characteristic foraminiferal, radiolarian assemblages and palynomorphs observed in the study area.

1992). In addition, the Kandahar Arc in eastern and central Afghanistan was erupted through the SW margin of the Eurasian Central Afghan Block (Tapponnier et al., 1981). Therefore collision of India with the Trans-Himalayan Arcs is equivalent to the collision of India and Asia. A second episode of deformation during the early Paleocene (Paleocene, Danian stage, zone P1 – P3) is suggested by rapid subsidence of the northwest continental margin beginning in the early Paleocene. Moreover, index fossils for the Pα, P1a, b, c, d, P2 and P3 biozones are absent in the mélange of the Thal area suggesting regional uplift during the Paleocene. This hiatus is regional and corroborated by the absence of diagnostic Danian (early Paleocene) foraminifera in over 200 biostratigraphic samples from the ophiolitic mélange and associated olistostromal facies. Middle Paleocene limestone containing basaltic clasts are reported from the Khost-Yaqubi area 47 km to the west in Afghanistan (Kaever, 1967a,b; Bruggey, 1973a; Bruggey et al., 1973b). Hence the initial collision might have occurred before or during the deposition of ultramafic bearing middle Paleocene conglomerates in eastern Afghanistan and before the regional deposition of Paleocene (zone P5) shales and limestone of the Chale Talao/upper Patala sequence. Finally, isoclinal folding and imbrication of very latest Maastrichtian basin fill occurred before the end of P5 (early Thanetian, early late Paleocene time) or approximately 60 Ma (time scale of Harland et al., 1989). Early Paleocene initial collision is also suggested by field paleomagnetic inclination-paleolatitude studies (Klootwijk et al., 1992), which indicate regional re- magnetization at latitudes which correspond with paleolatitude predicted by sea-floor magnetic anomaly studies (corrected to the hotspot reference frame) for the stratigraphically and radiometrically-metamorphically determined collision time window described above. Eclogites from Hazara, in northern Pakistan, (Tonarini et al., 1993) indicate minimum burial depths of 60 km and minimum temperatures of 650°C. Their peak metamorphism is dated at 49 Ma (Nd/Sm). They also concluded that initial collision must have been significantly earlier. The ophiolitic mélange and olistostromes with their late Paleocene strata were displaced farther onto the Indian craton in the Thal area between latest P6 and latest P9 time during the Ypresian (Early Eocene, P6-P9) before they were overlapped by unconformable middle Eocene limestones (Davies, 1926b). An asymmetric, flexurally subsiding marine foreland basin formed above the pre-existing Indian Shelf. Subsequently, the basin filled from subaerial craton and hinterland margins with fluvio- lacustrine sediment and evaporitic sequences before middle Eocene shallow marine limestones and shales overlapped the Indian craton, eroded igneous complexes and ophiolitic melange and olistostromes. A major unconformity is present between Late Cretaceous and Paleocene all over the Waziristan and Kurram area. The earliest microfauna of Paleocene observed from the surface samples are mainly larger benthic foraminifers of Late Paleocene (Thanetian stage). The presence of larger benthic foraminifers such as Miscellanea miscella, Lockhartia haimei and Rotalia trochidiformis indicates shallow marine high energy environment. In the later part of Paleocene there is a shift of environment from shallow to deep water as represented by the appearance of Planktonic foraminifers in the Patala, Panoba and Ghazij formations (Fig. 2-20). However the presence of larger benthic foraminifera

Figure 2-20: Depositional history of the syn and post collision strata exposed in the study area, deduced from the characteristic foraminiferal, radiolarian assemblages and palynomorphs observed in the study area.

in the limestones of the Patala and Chale Talao formations indicate a shallow water influx in deeper water conditions, therefore this particular interval is interpreted as outer shelf to slope turbidites. The maximum numbers of species are found in the Late Paleocene to Early Eocene sediments that indicate warm water conditions highly favorable for speciation. In the early part of the Early Eocene there is abundance of planktonic foraminifers, which represent an open marine environment in the Patala, Panoba and Ghazij Formations. While in the later part of Early Eocene there is a shift of environments again and larger benthic foraminifers are dominating, indicating shallow marine high-energy environment. In the early Middle Eocene there were shallower conditions as the presence of abundance larger foraminifers in Shekhan Limestone, Kohat Limestone and Spera Ghar Limestone. The transition from a collisional to transform plate boundary during the Eocene strongly influenced deposition in northwestern Pakistan. Initiation of the Gardez Fault after the middle Eocene created a wedge-shaped fragment of NW India, the Kabul Block (Boulin, 1991) (Fig. 2-23). This wedge drove the Spin-Boldak/Kandahar segment away from its ophiolite fringe, which had already been obducted onto the Indian Plate As the Kabul Block wedged India and the Central Afghan Block apart, a rhomb chasm formed generating the Katawaz Basin. NW-SE compression was accompanied by contemporaneous NE-SW extension (Cassaigneau, 1979). The Katawaz Basin is filled with Oligo-Miocene flysch and continental molasse above remnants of the Paleogene Indian-Eurasian suture. Late Eocene-Oligocene displacement of the Kabul Block and southward transpressional displacement of the Katawaz Sea accommodated Indian-Kabul Block convergence during a period of reduced subsidence and deposition along the NW Indian margin. Limited underthrusting of the floor of the Katawaz Basin beneath the SE Kabul Block may be responsible for the series of small Oligo-Miocene granitic intrusions along that margin (Cassaigneau, 1979; Boulin, 1991). Continued Neogene NW-SE transpression and infilling of the Katawaz Basin terminated marine sedimentation, initiated basin-wide continental sedimentation and has resulted in the development of a NW dipping cleavage in several areas of the basin (Jones, 1960; Andritzky et al., 1971; Andritzky, 1967; Schreiber et al., 1972; Bruggey et al., 1973b; Cassaigneau, 1979). Late Oligocene-Early Miocene closure of the Katawaz Sea uplifted and transpressionally deformed the Paleogene suture (Treloar and Izatt, 1993, Tapponnier et al., 1981; Pivnik and Sercombe, 1993). This renewed convergence resulted in development of the thin-skinned fold and thrust belt in eastern Pakistan and development of the present day Indus foreland basin. Renewed late Cenozoic thrusting in the region also uplifted the ophiolitic and deep-water allochthons originally emplaced during the Late Cretaceous and Early Tertiary. Although very little of the ophiolitic mélange and olistostromes remain in northern Pakistan and India, it is presumed that they once covered a much greater area and have since been eroded (Beck et al., 1995).

Figure 2-21: Paleogeographic map and cross-section of Waziristan and Kurram areas time. Cretaceous to Middle Triassic during

Figure 2-22: Paleogeographic map and cross-section of Waziristan and Kurram areas during Late Cretaceous ophiolite obduction.

Figure 2-23: Paleogeographic map and cross-section of Waziristan and Kurram areas during time. Paleocene-Eocene

CONCLUSIONS Extensive biostratigraphic work enabled to distinguish five tectonostratigraphic units and two significant unconformities in the study area. Foraminiferal zones from Early Jurassic to Middle Eocene have been identified, although due to random samples these zones are not continuous in the sedimentary record. However continuous biozones from Late Paleocene P4 to Early Eocene P9 (Bolli, 1985) biozones were recorded. Depositional history of the sedimentary record has been deduced from the environmentally diagnostic microfauna. These microfauna are susceptible to the environmental changes due to major tectonic events in the region. Triassic to Middle Cretaceous strata include inner shelf to slope facies of the passive margin of the northwest Indian craton with general westward deepening trend. Middle to Late Cretaceous collision of the Kohistan island arc with Asia shifted the subduction zone southward. The shift of subduction resulted tectonic loading and deep marine strata during this time deposited on the northwest Indian passive margin. This event was recorded by the olistoliths and turbidites present in the study area. Biostratigraphic results show that the major deposition took place during the Late Cretaceous time in an outer shelf to bathyal environment. These strata were previously assigned as shallow marine strata. Initial obduction of ophiolites onto the NW Indian craton occurred in the Late Campanian time (~74 Ma). A westward derived shallow marine siliciclastic Maastrichtian strata deposited above the ophiolites indicating the completion of the obduction before Maastrichtian time. It is observed that Santonian stage is generally missing in the normal sedimentary sequence and it is only found in the olistoliths. This implies that during the Campanian time there was instability in the shelf due to heavy oceanic crust rising on to the continental margin, which caused the displacement of the Santonian and at places older strata. There is a major unconformity at KT boundary, followed by a rapid subsidence during early Late Paleocene. This subsidence is resulted from the tectonic loading of ophiolites over the northwest Indo-Pakistani craton and created foredeep in the region. Unconformity above the Kahi Melange (Zone P4 & P5) represents the initial contact between India and Eurasia. Early Eocene strata preserved a reworked Cretaceous microfauna that is due to structurally partitioning of basin as a result of northward compressional and westward transtensional forces. The pull apart uplifted the Kohat area while the Waziristan area submerged and transtensional Katawaz Basin opened. Middle Eocene shallow marine limestone covered all areas of the Indo-Afghan suture zone indicating that the end of Early Eocene completed the suturing.

3. CHAPTER 3

BIOSTRATIGRAPHY OF UPPER CRETACEOUS OLISTOLITHS AND BRACKETING STRATA, MUGHAL KOT GORGE, BALUCHISTAN, PAKISTAN

INTRODUCTION For the last two decades there has been considerable debate over the timing of ophiolite obduction and initial collision with Asia along the northwest margin of the Indian continent (Stoneley, 1974 and 1975; Brookfield, 1977; Searle et al., 1987;Garzanti, et al., 1987; Robertson and Degnan, 1993; Beck et al., 1995). One school of thought suggests ophiolite obduction began along the western margin of the Indo- Pakistani craton during Late Cretaceous time (~80 Ma)(Stoneley, 1974, Beck et al., 1996), while others argue for a Paleocene age of obduction (Allemann, 1979, Cassaigneau, 1979, Mahmood et al., 1995). Each interpretation has implications towards the Late Cretaceous and Paleocene geologic history of the region and the kinematics evolution of the Himalayan orogen, in general, and geometries for the region. Controversy continues because of the complex geology of the region and lack of good biostratigraphic constraints in the sedimentary rocks contained in the suture zones between India, Asia and the accreted oceanic terrain of the greater Himalaya (Gansser, 1964; Burg and Chen, 1984; Searle, 1986). Although biostratigraphic data may help constrain the age, depositional environments and paleogeographic setting of rocks contained in a suture zone, data from such a tectonically complex zone may, however, be difficult to interpret. Most suture zone sedimentary units are highly deformed, and commonly displaced from their original depositional positions. In addition, the age of the rocks themselves commonly provide only a maximum age of deformation with in the suture zone. The depositional history of areas adjacent to an active suture zone, however, may help constrain the timing of obduction and collision. The age of strata containing evidence for rapid deepening, collapse features and, compositional changes in coarse-grained clastics can be used to decipher the chronology of obduction and collision. This chapter establishes a detailed biostratigraphic framework for a key section of Cretaceous – Early Tertiary strata originally deposited along the Northwest margin of the Indo-Pakistani craton. These rocks, exposed in the Mughal Kot Gorge in northwestern Pakistan, contain lithologies (olistoliths and coarse volcaniclastics) that have been interpreted as being deposited during the initial obduction of ophiolites onto the Indo- Pakistani margin. The purpose of this study is to determine the biostratigraphic age of the Mughal Kot section, identify temporal changes in sediment accumulation rates and relative sea level, and compare these dates with the radiometrically-constrained obduction history of the Waziristan Ophiolite Complex in Northwest Pakistan. The detailed biostratigraphy presented here clarifies the Late Cretaceous through Middle Eocene depositional history of the Northwest Pakistan and provides insights into the timing of ophiolite obduction and initial India-Asia collision.

Regional Tectonic Framework The Mughal Kot Gorge is situated near the northeastern terminus of Sulaiman Fold and Thrust Belt, in northwestern Pakistan (Fig. 3-1). The thrust belt contains strata originally deposited along the western margin of India during Mesozoic and Tertiary time. The thrust belt is bounded to the east by the Indus Basin and to the west by the Muslim Bagh and Waziristan ophiolites and the Katawaz Basin. The ophiolites of the region are interpreted as segments of oceanic crust that were thrust on to the rocks of the Indian continental margin prior to the collision of India and Eurasia (Beck, 1995). Following obduction collision and oblique convergence between India and Eurasia along the western margin resulted in the tectonic segmentation of the accreted ophiolitic terrains, and development of the Katawaz Basin in board of the left-lateral Chaman Fault (Beck et al., 1996). Continued oblique convergence during the late Tertiary led to the generation of the present day fold and thrust belt.

METHODS AND DATA

Biostratigraphic Methods This study focused on the well-documented and minimally deformed Mesozoic - Tertiary section at Mughal Kot Gorge (Fig. 3-1). Samples were collected from the Parh Limestone, Mughal Kot Formation, Pab Sandstone, Ranikot Formation, Dunghan Limestone, Ghazij Shale and Kirthar Formation (Fig. 3-2). Samples were taken from characteristic lithologies of these units and from olistoliths present in the Mughal Kot Formation. The collected samples were labeled Mk-1 to Mk-70 and Gz -1 to Gz -5.

Sample Preparation Biostratigraphic samples were divided into two categories, soft samples such as marl and shale, and hard samples such as limestone, sandstone and chert. About 200 grams of soft sample were used to prepare slides of microfossils. The samples were treated with 25% hydrogen peroxide (H2O2) and a few drops of ammonia (NH4OH) to defloculate the samples. The deflocculated samples were washed through a 63µm sieve. Washed residues were treated in an ultrasonic bath for 5 minutes for further cleaning and dried afterwards in an oven at 80o C. Samples were then stored in properly labeled vials for the study. A binocular light microscope was used to examine approximately 300 specimens of foraminifers from each sample and preserved in slides designed for microfossil analysis. Hard samples were thin sectioned and studied directly under polarized light microscope.

Identification of Microfossils The microfossil residue was separated into four grain-size classes (>63µm, >125µm, >250µm, >630µm) for ease of handling. The planktonic foraminifers were identified following the species and zonal concepts of Caron (1985), Toumarkine and Luterbacher (1985), Blow (1979) and Berggren et al. (1993). The smaller benthic foraminifers were identified after Loeblich and Tappan (1988) and Jenkins and Murray

Figure 3-1: Simplified geologic map of Pakistan showing regional structural elements and study area. M.K.T., Main Karakoram Thrust; M.M.T., Main Mantle Thrust; P.P.T., Pir Punjal Thrust; M.B.T., Main Boundary Thrust; Sulaiman F.T.B. Sulaiman Fold and Thrust Belt; J.M. ARCH, Jacobabad Mari Arch; O.N.F., Ornach Nal Fault; WO, Waziristan ophiolites; KO, Khost ophiolites; MBO, Muslimbagh ophiolites; BO, Bela ophiolites (after Beck et al., 1996b).

Figure 3-2: Geological Map of the Mughal Kot Gorge area (after Hemphill and Kidwai, 1975). Lithologic symbols used in this map are adopted in all other figures.

(1989). The larger benthic foraminifers were identified after Davies (1937 b), Smout (1954) and Weiss (1988).

Zonal Scheme Several planktonic foraminiferal zonal schemes are currently in use for the Cretaceous and Tertiary (Premoli Silva and Bolli, 1973; Stanforth et al., 1975; Blow, 1979; Toumarkine and Luterbacher, 1985 and Berggren and Miller, 1988). Berggren and Norris (1993) revised their zonal scheme and redefined some of the early Paleocene zones. A correlation of all of these zonal schemes as illustrated in Fig. 3-3 is followed in this study. The correlation is based mainly on the association of larger benthic foraminifers and planktonic foraminifers found in the region.

Chronobiostratigraphy Planktonic foraminiferal datum levels and faunal events for Cretaceous and Tertiary strata have been used in correlating sedimentary sequences and building age models (Miller et al. 1987; Corefield, 1987; Park and Miller, 1992; Lu and Keller, 1993). The datum levels used in this study are zonal boundary marker foraminifers. The first occurrence and the last occurrence of significant species were considered secondarily. Chronological calibration of the datum line and faunal events in this study are based on the magnetostratigraphy by Bleil (1985). The stratigraphic age of samples were assigned based on characteristic zonal marker species and the first occurrence (FO) and the last occurrence (LO) of any diagnostic species identified. All age assignments in this study have been adjusted to the time scale of Harland (1990) for consistency with previous work.

Paleoenvironment The planktonic to benthonic ratio in foraminiferal quantitative analysis helps determine depositional environment. However, interpretation of P: B data may be problematic because productivity of planktonic and benthonic foraminifers is influenced by physical, chemical and biological factors. The two significant processes that control P:B ratio are sea-level change and paleoproductivity (controlled in turn by nutrition factors). If water mass properties are controlled mainly by water depth and related physicobiochemical parameters then the distribution patterns of planktonic and benthonic foraminifera may vary in a predictable fashion along a depth gradient. In this case, an increase in planktonic foraminifera will indicate greater water depths because planktonic species are mainly found in the open marine environment. Alternatively, an increase in benthonic foraminifera suggests reduced water depth, as they are abundant in neritic environments (Phleger, 1964). As such, in this study an observed change in P: B ratio was interpreted as deepening or shallowing of paleowater depth. However, the variation in P: B ratio does not provide numerical depth information and is used only as an indicator of change in relative paleobathymetry.

Figure 3-3: Zonal Correlation used in this study, (1) numerical ages, chrons and polarity are assigned (after Harland et al., 1990); (2) planktonic foraminiferal zonation scheme for Paleocene and Eocene by Berggren et. al., (1995) and for Cretaceous by Caron (1985); (3) larger benthic association scheme adopted after (Weiss, 1988); (4) Radiolaria zones assigned (after Sanfilippo and Riedel, 1985)

Stratigraphy of the Mughal Kot Gorge

The oldest rock exposed in the Mughal Kot Gorge section is the Jurassic Sulaiman Limestone Group. This unit is disconformably overlain by the Cretaceous Sembar Formation, Goru Formation, Parh Limestone, Mughal Kot Formation and Pab Sandstone. The Paleocene Ranikot Formation, Dunghan Limestone and Lower Ghazij Shale unconformably overlie the Cretaceous strata. The Eocene Upper Ghazij Shale and Kirthar Formation conformably overlie the Paleocene succession. A brief description of these rocks is provided in the following paragraphs:

Sulaiman Limestone Group: The Sulaiman Limestone Group consists of the Spingwar, Loralai and Anjira formations. Lithologically the unit is made up of hard, fetid, thin to massive bedded, dark gray to blue oolitic limestone, contains some secondary calcite and chert nodules. Blue black calcareous claystone intercalations are common in the lower part of the unit. The lower contact is not exposed and the upper contact is disdconformable with the Sembar Formation. Macrofossils of the Sulaiman Group include ostracods, algae, corals, bryozoans, brachiopods, mollusks, crinoids and foraminifers. These fossils indicate that Sulaiman Group was deposited in a shallow marine environment and are Early – Middle Jurassic in age (Shah, 1977).

Sembar Formation: The Neocommian Sembar Formation consists of black soft shale, claystone with thin beds of nodular limestone and sandstone (William 1959). The lower contact is unconformable with Sulaiman Limestone and the upper contact with Goru Formation is gradational. Fossils in the Sembar Formation consist of ammonoids, foraminifers and nannofossils. The depositional age of the Sembar Formation spans the entire Neocommian (Early Cretaceous) time and the paleoenvironmental setting is interpreted as shallow marine to open marine (Bender and Raza, 1995).

Goru Formation: The basal part of the Goru Formation consists of predominantly light to medium gray, thin-bedded fine-grained limestone with minor shale intercalations. The abundance of limestone beds decreases upward and is replaced by interbedded shale and marl. In the upper most part the concentration of limestone increases again and is gradational with the overlying Parh Limestone. Fossils in the Goru Formation consist of abundant pelagic foraminifers and nannofossils and indicate an Albian – Cenomanian, (Middle Cretaceous) age of deposition. The depositional environment of the formation varies from shallow marine to more open marine toward the top (Shafique and von Daniels, 1990).

Parh Limestone: The Parh Limestone is a hard, well bedded, lithographic to porcellaneous, limestone with marl intercalations (Williams, 1959). The unit is light gray, and cream to tan in color. The upper contact is conformable with the overlying Mughal Kot Formation. The Parh Limestone is highly fossiliferous and yielded abundant planktonic foraminifers and nannofossils. Based on the fossil assemblage present in the unit the Parh Limestone is Turonian to Campanian (Late Cretaceous) in age (see below). The depositional environment is interpreted as open to deep marine.

Mughal Kot Formation: The Mughal Kot Formation is composed generally of dark gray calcareous mudstone with scattered intercalations of sandstone, conglomerate, and argillaceous limestone. The interbedded sandstone is a medium to dark gray sublitharenite to litharenite that contains volcanic rock fragments. Sandstone and conglomerate interbeds fine upward and contain typical Bauma turbidite subdivisions. The Formation locally contains olistostromes and pebbles of basalt. The upper contact with Pab Sandstone is gradational. Fossils in the Mughal Kot Formation include smaller benthic and planktonic foraminifers that indicate a Campanian – Maastrichtian (Late Cretaceous) age of deposition (see below). Deposition of the Mughal Kot Formation is interpreted as occurring in an outer shelf – open marine environment.

Mughal Kot Olistoliths Olistoliths in the Mughal Kot Formation are prominent and range from 2-30 meters in diameter. The samples were thin-sectioned, and their petrography and biostratigraphy was compared with the underlying pelagic shelf limestone (Burris et al., 1996). The composition of the olistoliths is identical to the underlying Parh Limestone and primarily consists of pellets, gastropods and foraminifers. The foraminiferal assemblage contained in the olistoliths is similar to that contained in the underlying Parh Limestone The shale and mudstone layers of the Mughal Kot Formation that enclose the olistoliths are isoclinally folded. However, thin, undeformed sandstone interbeds indicate that deformation of the shale occurred during deposition and not during some later event (Burris et al., 1996). The orientations of numerous flute casts were measured on the basss of the thin undeformed sandstone units, present in the section. The flute casts indicate flow to the west off the Indian craton, towards the present position of the ophiolites.

Pab Sandstone: Pab Sandstone is a gray to brown, thick to massive bedded quartzose sandstone with intercalation of shale and silt. The upper contact with Ranikot Formation is disconformable. At the Mughal Kot section the Pab Sandstone is devoid of fossils. However, based on the fossils recorded from other localities the Pab Sandstone is Maastrichtian (Late Cretaceous) in age (Shah, 1977).

Ranikot Formation: The Ranikot Formation consists of variegated thick-bedded sandstone and shale with inter-bedded limestone and basaltic lava flows. The shale is dark colored and highly carbonaceous and locally contains coal seams (Williams, 1959). The lower contact with Pab Sandstone is unconformable and the upper contact with Dugan Formation is conformable. Ranikot Formation yielded a few foraminifers that indicate an Early to Middle Paleocene age of deposition. The Ranikot Formation is interpreted as being deposited in a shallow marine to terrestrial depositional environment.

Dunghan Formation: The Dunghan Formation is a medium grained hard, dark gray very thick-bedded fossiliferous limestone with subordinate shale, marl and intra-formational conglomerate. The shale is greenish gray, calcareous, splintery and fossiliferous. The lower contact with Ranikot Formation is conformable and the upper contact with Ghazij Formation is also conformable. The formation is rich in larger benthic foraminifers that indicate a Middle Paleocene age of deposition in a high energy, shallow marine environment.

Ghazij Formation: Gray to olive gray shale with subsidiary beds of limestone and sandstone make up the Ghazij Formation (Oldham, 1892). The shale is commonly irregularly bedded, fissile to papery, and silty and ranges from dark gray to olive green in color. The sandstone, which is largely confined in the upper part of the formation, is generally regularly bedded, soft and poorly sorted. Limestone beds are thin and light to dark gray in color, and commonly marly to argillaceous. The upper part of the formation is gypsiferous and contains coal beds. The upper contact with Kirthar Formation is conformable. The lower part of the Ghazij Formation is fossiliferous and contains foraminifers and nannofossils, which indicate Late Paleocene-Early Eocene age of deposition in an open marine environment. The upper part of the formation is barren of microfauna and, based on the gypsiferous beds and coal seams, was deposited in a shallow marine lagoonal to deltaic environment.

Kirthar Formation: The Kirthar Formation consists of four members: The Habib Rahi Member; which is a grayish brown thin to thick-bedded limestone; the Domanda Member; which is a dark brown to greenish gray claystone; the Pirkoh Member; which is a brown gray to white limestone with subordinate of argillaceous limestone; and the Drazinda Member; which is a brown to gray clay with subordinate marl and sandstone. These members conformably overlie the Ghazij Formation. The Kirthar Formation contains larger benthic foraminifers, which indicate an Early to Middle Eocene age of deposition. Deposition of the Kirthar Formation is interpreted as occurring in a shallow marine, inner shelf paleoenvironment.

Radiometric Constraints on the Ophiolites Radioisotope dating has been used to date metamorphism of the subophiolitic metamorphic rocks from the bases of the Bela, Muslimbagh, Khost and Waziristan ophiolites (Fig. 3-1). Glaucophane crystals in metatuff beneath the Khost ophiolite in Afghanistan yielded a date of ~ 70 Ma (Taponier et. al., 1981). However more recent single crystal 40Ar/39Ar dating of hornblende in the metamorphic sole of the Waziristan ophiolite yielded ages of ~96-90 Ma (Gnos, 1997 and 1998). Post emplacement felsic intrusions which cross-cut the tectonically stacked ophiolite within the Waziristan ophiolite complex yield 80 Ma 40Ar/39Ar ages (Gnos et al., in review), provide a minimum age of obduction.

RESULTS

Biostratigraphic Data The results of biostratigraphic analyses and stratigraphic ranges are tabulated in a range chart (Fig.3-4 and 3-5). The horizontal bars represent the frequency of each microfauna found in the samples. Biozones were identified based on characteristic zonal fossils, and the first, or the last occurrence of marker species.

Biozones Parh Limestone Based on the foraminiferal fauna yielded from samples of the Parh Limestone, the unit can be divided into three distinct biozones, the Helvetoglobotruncana helvetica zone of Late Turonian stage, the Dicarinella primitiva zone of Early Coniacian stage and the Globotruncanita calcarata zone of Late Campanian stage. Late Coniacian, Santonian and Early Campanian stages were not found because of large sampling interval, however these stages are recorded in the Parh Limestone at Murree Brewary section (southwest of the study area Fig. 3-9) in the Parh Limestone (Weiss, 1992).

Mughal Kot Olistoliths Olistolths of the Mughal Kot Formation contained a planktonic foraminiferal assemblage consisting of Heterohelix reussi, Globotruncana bulloides, G. linneiana, G. lapparenti, and Rosita fornicata. Based on the last occurrence of Heterohelix reussi and the first occurrence of Globotruncana bulloides the olistoliths can be placed in the Late Santonian, Dicarinella asymetrica zone.

Mughal Kot Formation The Mughal Kot Formation can be divided into two distinct biozones, the Globotruncanita calcarata zone of the Late Campanian and the Globotruncan aegyptiaca zone of the Early Maastrichtian.

Pab Sandstone The samples collected from the Pab Sandstone were barren of microfauna. The frequent occurrence of sandstone and coarser shale reflects very near shore to terrestrial environment, which prohibited the preservation of microfauna.

Ranikot Formation Only one sample from the top of Ranikot Formation, Mk-45, yielded a few planktonic foraminifers of the Early Paleocene Turborotalia compressa zone (P1C).

Dunghan Limestone

No characteristic planktonic foraminiferal were identified from the Dungan Limestone. However, on the basis of the larger benthic foraminiferal assemblage association, the Dungan Limestone falls completely within the Miscellanea miscella association zone, which is equivalent to the P5-P6 planktonic foraminiferal zone.

Ghazij Formation The lower part of the Ghazij Formation yielded few planktonic foraminifers but these were not age diagnostic therefore it was not possible to assign zonation for this unit in this section. However a few samples from the Ghazij Formation did yield a few reworked Cretaceous radiolaria

Kirthar Formation Two larger benthic foraminiferal species, Alveolina elliptica and Discocyclina dispensa are abundant in the Kirthar Formation. Therefore the Kirthar Formation can be placed within the Eocene Alveolina elliptica (~ P8 - P12 zone) and Discocyclina dispensa (~P10 – P14) association zones (Weiss, 1988).

Figure 3-4: Cretaceous Foraminiferal Distribution Chart of Mughal Kot Section. Numerical ages are assigned (after Harland et al., 1990).

Figure 3-5: Tertiary Foraminiferal Distribution of Mughal Kot Section. Numerical ages are assigned (after Harland et al., 1990).

Bioevents

A foraminiferal range chart for the Indo-Pakistani shelf sequence at the Mughal Kot Gorge and Mughal Kot Formation type-section is shown in Figures 3-4 & 3-5. Biozones identified in the strata are based on the presence of zonal index fossils classified by Caron (1985) and Toumarkine and Luterbacher (1985). Continuous biozones for the Santonian-Campanian interval were observed, but very few microfauna were observed above the lowest Maastrichtian strata. This faunal decrease is inferred as the first bioevent in the upper Cretaceous – lower Tertiary sequence at Mughal Kot. A decrease in the size of the planktonic foraminifers in the lower Paleocene strata indicates another bioevent related to environmental instability such as decrease in nutrient or abrupt climate change.

Paleoenvironment and Bathymetric Distribution Paleoenvironment can generally be deduced from the qualitative and quantitative analysis of planktonic and benthic foraminifers. The planktonic/benthic ratio is a useful means of estimating the distance from the shoreline. In the Parh Limestone (Coniacian- early Campanian) the P: B ratio is high with planktonic foraminifers dominant indicating an open marine environment away from the shoreline (Fig. 3-6). In contrast, at the base of Mughal Kot Formation (Campanian), where olistoliths are found, the P: B ratio is low indicating shallow water or downslope movement of benthic foraminifers. In this part of the section, turbiditic sandstone containing A, B and C Bouma units were observed, indicating the possibility of downslope benthic foraminiferal transport (Bouma, 1985). In the overlying strata of Mughal Kot Formation higher P: B ratios suggest renewed open marine conditions. In the qualitative analysis of the Turonian-Campanian planktonic assemblages, double-keeled Globotruncanids are dominant in the pre-Santonian strata, suggesting deeper water conditions as compared Campanian strata. The presence of these species indicates a relatively high sea level favorable for the deposition of pelagic carbonate. A small regressive phase or supply of allochthonous benthic foraminifers in the upper Mughal Kot Formation followed this interval. An analysis of foraminiferal diversity in the section at Mughal Kot yielded the following results: 1) The number of planktonic and benthonic foraminiferal species per sample (Fig 3-4) reached maximum at the beginning of the Late Campanian indicating a warm period that was favorable for speciation; 2) Quantitative analysis of Tertiary samples indicates that there was a relative rise in sea level during the Early Paleocene as indicated by the sudden appearance of planktonic foraminifers above Maastrichtian strata. In contrast, the presence of larger benthic foraminifers in the Middle Paleocene is indicative of a shallow marine inner shelf environment within the photic zone (100-150 m water depth) suggesting a relative drop in sea level; 3) Early Eocene deposition occurred in a shallow marine near shore environment, as indicated by the scarcity of planktonic foraminifers relative to benthic foraminifers and the presence of gypsum in the upper Ghazij samples. The early Middle Eocene Kirthar Limestone yielded abundant larger benthic foraminifers that indicate a high energy, inner shelf environment.

Summary of Biostratigraphic Events Foraminiferal biostratigraphy of the study area has provided stratigraphic age control and revealed paleoenvironmental changes from the Turonian to the Early Tertiary. These environmental changes may be related to four local tectonic events that occurred in the Tethys as well as global events including the Cretaceous Tertiary boundary event. 1. Microfauna extinction began at the end of the Early Maastrichtian stage and continued across the Cretaceous-Tertiary boundary until Early Paleocene time. 2. The size of foraminifers, found in lower Paleocene strata, is abnormally small which indicates possible paleoenvironment stress during the Early Paleocene. 3. The presence of reworked Cretaceous radiolaria in Early Eocene strata implies a source of uplifted Cretaceous strata. 4. The rate of sedimentation in the Late Campanian was high as inferred from the ~ 1000 m (Table 3-1) thick Globotruncanita calcarata interval zone (80 – 74 Ma) (Caron, 1985). Given the marine depositional environment, this indicates relatively rapid subsidence and accommodation of sediments in the basin (Fig. 3-7).

Sea-level History There are four significant sea-level changes (Fig.3-6) that can be interpreted from the present foraminiferal study of the Mughal Kot section: 1. In the Campanian there was an influx of allochthonous benthic foraminifers as indicated by the decreasing P: B ratio. 2. In the Late Maastrichtian time, there was a marked fall of sea level as indicated by the absence of marine microfauna. 3. During the early part of Paleocene, there was a relative rise of sea level as indicated by the reappearance of planktonic foraminifers. 4. At the end of the Early Eocene, there was a short-term fall and then rise of sea level where unfossiliferous gypsiferous beds of Ghazij Shale are overlain by highly fossiliferous larger benthic foraminiferal Habib Rahi (Kirthar) Limestone (Fig.3-7).

Figure 3-6: Sea level history at Mughal Kot Section deduced from P:B ratio of Foraminiferal Biostratigraphy. Numerical ages are assigned (after Harland et al., 1990).

Formation Thickness Thickness Sed. starts Sed. ends Duration Sed. Rate (m) (km) (Ma) (Ma) (Ma) (km/Ma) Habib Rahi 30.32 0.030 45.0 42.5 2.5 0.012 Ghazij 2892.26 2.892 55.0 45.0 10.0 0.289 Dungan 67.82 0.068 60.5 55.0 5.5 0.012 Ranikot 89.45 0.089 65.0 60.5 4.5 0.020 Pab 224.42 0.224 74.0 65.0 9.0 0.025 Mughal kot 922.33 0.922 80.0 74.0 6.0 0.154 Goru/Parh 348.54 0.349 112.0 80.0 32.0 0.011

Table 3-1: Rate of Sedimentation in the Mughal Kot Gorge estimated from the sedimentary thickness vs. depositional time.

Subsidence History of the Mughal Kot Section

0 0.5 Obduction related 1 Passive margin subsidence flexural subsidence 1.5 2 2.5 Initial collision 3 related flexural 3.5 subsidence

Thickness (Km) 4 4.5 5 120 110 100 90 80 70 60 50 40 Time (Ma)

Figure 3-7: Subsidence history at Mughal Kot Section deduced from the Foraminiferal Biostratigraphy. Three subsidences, passive margin, ophiolite obduction related and subsequent collision related subsidences are observed. Numerical ages are assigned (after Harland et al., 1990).

Figure 3-8: Regional biostratigraphic compilation of the Mughal Kot section and Waziristan area, (1) metamorphic ages based on single crystal Ar/Ar radiometric studies of hornblende in the metamorphic sole of the Waziristan ophiolite (90-96 Ma) (Gnos, 1997 and 1998); (2) radiometrically dated cross-cutting relationship (80 Ma) (Gnos, 1997 and 1998). Numerical ages are assigned (after Harland et al., 1990).

Figure 3-9: Localities of olistoliths found in the Mughal Kot Formation in the NW Pakistan (after Burris et al., 1996).

Interpretation The cross-cutting relation ages from the Waziristan ophiolites (80 Ma, Ar/Ar radiometric ages) are consistent with the biostratigraphic age of the matrix surrounding the olistoliths at Mughal Kot Gorge. Syndepositional folding, petrography, and paleocurrents associated with the Santonian – Campanian olistoliths suggest regional collapse of the NW Indo-Pakistani shelf during Late Cretaceous obduction of ophiolites. Accelerating subsidence beginning near the Santonian/Campanian boundary and is interpreted as the result of tectonic loading. The tectonic loading is interpreted as a result of the northward movement of the Indian Craton beneath fragments of Tethyan Oceanic crust now represented by the Waziristan ophiolite. By Late Campanian time (~80 – 74 Ma) the tectonic loading of the ophiolites was great enough to induce regional collapse of the continental shelf, possibly through the reactivation of pre-existing passive margin normal faults. The syn-obduction foredeep filled gradually with volcaniclastic sandstone during the Campanian-Maastrichtian (Fig. 3-8) (Beck et al., 1996). Although this study focused on biostratigraphically constraining the timing of olistostromes deposition and its possible relationship to the ophiolite obduction it also has important implications for the timing of the India-Asia collision. However, a stratigraphically discrete Paleocene deformation event in Kurram to the north of Waziristan is securely dated as P3-P5 (Middle to Late Paleocene) and immediately follows rapid acceleration in the rate of subsidence of the NW corner of the craton (Beck et. al., 1996a). This event coincides with compressional deformation across much of Afghanistan and eastern Iran (Stocklin, 1974, 1977) and is interpreted as the result of incipient India-Asia collision (Beck et al., 1996a,b).

CONCLUSIONS Upper Cretaceous to Lower Tertiary strata from the Mughal Kot section was studied in order to determine the depositional history of the region. Biostratigraphic analysis of these rocks identified five distinct biozones from the Upper Cretaceous strata and one distinct Early Paleocene (P1C) zone from the Lower Tertiary strata. A Late Santonian age (D. asymmetrica zone) was determined for olistoliths present in the lower Mughal Kot Formation. These olistoliths were deposited in the lower Mughal Kot Formation during Campanian time (G. calcarata zone). Similar olistostromes are found in the Mughal Kot Formation throughout NW Pakistan (Fig.3-9). Regional collapse of the NW Indo-Pakistani shelf margin occurred during the Late Campanian (~ 80 – 74 Ma). Due to the stratigraphic age of olistolith deposition this collapse is interpreted as being related to the tectonic loading during ophiolite obduction as the Indo-Pakistani craton moved beneath Tethyan oceanic crust along its NW margin. The evidence presented here indicates a discrete episode of accelerated subsidence and olistostromes deposition, presumably in response to ophiolite obduction, during the Late Cretaceous. The timing of this event is several million years before regional Paleocene deformation interpreted as incipient India-Asia collision.

4. CHAPTER 4

INTEGRATION OF BIOSTRATIGRAPHY, LITHOSTRATIGRAPHY AND REMOTE SENSING VIA GEOGRAPHIC INFORMATION SYSTEMS TO CONSTRAIN THE REGIONAL TECTONICS OF NW PAKISTAN

INTRODUCTION The biostratigraphy of sedimentary rocks can be reliable tool in constructing the structural configuration of orogenic belts. Biostratigraphic data can help constrain the age of strata, and in turn, help determine stratigraphic and/or tectonic position of deformed strata. Biostratigraphic data by themselves, however, are not sufficient to construct geologic maps and cross-sections of mountain belts. To construct sound geologic maps and cross-sections, biostratigraphic data must be combined with lithologic, structural and other types of geologic information. Remote sensing and geographic information systems (GIS) provide efficient ways in which to integrate biostratigraphic data into a broader geologic context. In this chapter an example of a study is presented, which integrates a large quantity of biostratigraphic data to enhance and revise existing geologic maps of the Himalayan orogenic belt in northwestern Pakistan. This integrated data can in turn be used to help interpret the geologic and tectonic history of the region A geographic information system (GIS) is a computerized tool for characterizing landscapes, which allows quantitative analyses of environments ranging from natural ecosystems to urban areas. The analytical ability of GIS has typically been used in fields such as earth science, forestry, agriculture, water resource management, urban planning, facility sitting, and environmental protection. Applications of GIS technology are numerous and the use of GIS has grown dramatically, creating a multi-billion dollar, international industry. GIS is beginning to be applied to true geologic data integration such as structural, stratigraphic and mineral exploration mapping. In the past, such use was concentrated on the development of land use and land coverage studies (Rains et. al., 1997). The present study is one of the first to use GIS to synthesize a wide variety of geologic data in a spatial context and integrate it with remote sensing data. Maps, which are input into a GIS, will almost invariably be compiled with different projections, datum, and scales. In order to consistently handle these data, GIS software includes functions for converting between map projections and for precise realignment of mapped features based on selected control points identified in each of the map layers (Write and Stewart, 1990). Individual maps in the GIS may have their characteristics manipulated by renaming categories (e.g. forest & agriculture -> land; lakes & streams -> water) or using mathematical operations (e.g. feet to meters). Proximity may be tested using functions which calculate distances between features or which can create buffer zones around them. The relationship between proximate features in a map can also be calculated to provide new information. For example, pixels

containing elevations in a raster dataset can be analyzed with respect to their neighbors to determine the local slope and aspect of the landscape (Aronoff, 1993). The true strength of GIS, however, is in its ability to perform overlay operations between map layers. In cases where map features represent discrete categories, overlay operations can determine the intersection or union of features from different map sources.

Maps representing numerical values may also be combined using mathematical relationships. As an example, a GIS may be used to find a contact boundary between two formations with the help of map layers for lithology, age, and paleoenvironment. These maps could then be combined mathematically to create a derived map indicating the regional geology (Walker et. al., 1996). Remote sensing data, and map products derived from remote sensing, are usually critical components of a GIS as the accuracy of the final GIS product heavily relies on this data (Star et. al. 1997). Several data structures have been developed for manipulating map-based data in a GIS. These structures fall within two predominant data models, either field-based or polygon-based. The first data structure is a raster data structure, the satellite data and scanned maps of an area fall into this category. The second data structure is vector data structure This study relies heavily on a geographic information system to facilitate the integration and analysis of a wide variety of laboratory and remote sensing data. Following the GIS methodology and using Arcview-3.1 software from ESRI, a GIS based layer model (Polygon based) of the study area was constructed. Thematic layer names used in the study the raster layers (consisting of the processed image layer and previous scanned map layer), and a vector layer (containing the analytical database termed the sample layer). In integrating these three layers, a set of polygons for each distinguishing stratigraphic unit exposed in the area has been constructed.

METHOD AND DATA

Overview

A geographic information system (GIS) is a computer system for managing spatial data. The word geographic implies the location of data in the real world in terms of geographic coordinates (latitude, longitude, datum). The word information implies that the data is organized to yield useful knowledge in the form of maps, images and also statistical graphics, tables, and various onscreen responses to interactive queries. The word system implies that the integrated geographic information consists of set of several interrelated and linked components with different functions. Construction of the GIS for the geologic mapping of the study area required three main steps (cf. Bonham-Carter, 1994):

Step 1 Step 2 Step 3

Build Data Integration Spatial Processing Models Database

The GIS allows data to be compiled, analyzed and modeled in an integrated fashion. In addition, data sets from different sources and of variable type can easily be incorporated into the system. Arcview 3.1 software by ESRI was used in this study for the GIS analysis.

Building a Spatial Database The initial database-building step required the establishment of the spatial extent of the study area, deciding an appropriate working projection, and assembling the various spatial data to be used in the study in digital form, properly registered so that the spatial components overlapped correctly. Three main spatial data sources were utilized in this study. These consisted of 1) analytical data tabulated with respective geographic coordinates, 2) digitized geological maps of the area, and 3) Landsat-5 Thematic Mapper TM image scenes. All data were compiled in Universal Transverse Mercator UTM Zone- 42N coordinate system using the WGS-84 datum. Considerable effort was made to consistently document the petrography and biostratigraphy of the sample set in a consistent text-based catalog. The text-based catalog was then parsed into an Excel spreadsheet. The Excel spreadsheet was then converted to a database format for ease of inclusion in a GIS. A database (ACCESS) has been established on the basis of analytical results. The sampling position with respect to longitude and latitude in the real world, geologic contacts, formations, localities and all other relevant information are stored in the database.

Attributes of Geological & Analytical Data A very powerful feature inherent in vector-based GIS system is the capacity to assign complex attributes for geologic information. For example, different line types are used for geologic Formation contacts that are well exposed (solid lines) vs. those that are approximate (dash line) and those that are inferred or concealed (dotted line). The assignment of geological information is the key element to using GIS packages with geologic and remote sensing data; no modification to the software is necessary. In addition values were assigned to the point data (e.g. bedding orientation, planar features etc). The point data was imported into Arcview as event theme. Table-4-1 represents some of the attributes that can be utilized in the GIS analysis.

Digitization of Previous Maps Several available previous geological maps were digitized with a digital scanner at appropriate resolutions and saved as a JPG raster format images. In most cases, due to their large size, each map was scanned in pieces as separate files. Afterwards these pieces were combined into a single file. The scanned maps were imported into the ENVI-3.1 software program and georeferenced with satellite image scenes. The georeferenced files were then exported into Arcview as raster layers using the Arcview BIL format.

Polygon # Formation FORMATION Lithology # Lithology Age # Age # NAME

1 2 Murree Sst. 2 Sandstone 4 Miocene 2 3 Kohat Lst. 3 Limestone 5 Eocene 3 4 Panoba Shale 4 Shale 5 E-Eocene 4 1 Siwaliks 1 Detrital 3 Pliocene 5 1 Siwaliks 1 Detrital 3 Pliocene 6 5 Patala Shale 4 Shale 6 Paleocene 7 1 Siwaliks 1 Detrital 3 Pliocene 8 2 Murree Sst. 2 Sandstone 4 Miocene 9 4 Panoba Shale 4 Shale 5 E-Eocene 10. 6 Lockart Lst. 3 Limestone 6 M-Paleocene

Table 4-1: A sample list of the individual polygons used in the GIS of the study area. A code # is assigned for common attributes, such as of lithology and age, for each map unit.

Remote Sensing and Image Processing

Overview

Spatial analysis requires the processing of satellite images of the area, database design, and attribute assignment to the analytical and geological data. Available landsat images of the area were processed using ERMapper 6.0 & ENVI 3.1 software. The purpose was to extrapolate the limited amount of data collected from the study area and adjacent regions with little or no previous geologic research. The first step was to identify the different lithological units exposed in the area. Vector layers relating the attributes of these lithological units were overlaid on the processed images. Satellite image data from the Landsat-5 Thematic Mapper (TM) database enables different rock types to be distinguished based on their characteristic spectral signatures (Rothery, 1990). The Landsat 5 TM scanner collected the data used in this study. The TM scanner is a multispectral scanner that collects radiation in a whiskbroom manner. The solid-state sensors collect specific bands of electromagnetic spectrum. There are seven scanners that collect seven bands. The position of these bands in the electromagnetic spectrum is between the visible and thermal infrared region. Each collector records total reflectance of its particular band. A Digital Number (DN), proportional to the total reflectance, was assigned and stored as one pixel for each band. The pixel size for the TM is 28.5 X 28.5 meter. Each image covers 185 X 170 km (Vincent, 1997). Four TM scenes (LT5151037009814310, LT5151038009814310, LT5152037009211810 acquired on 5/23/98 and LT5152038009216610 acquired on 04/27/92) were used in this study. The images were processed using ERMapper-6.0 and ENVI 3.1 image processing software. Band combinations, spectral ratios, principal component analysis and decorrelation stretch analysis methods were applied to the data to resolve lithologic variations in the study area.

Spectral Absorption and Signatures Spectral reflectance is controlled by absorption features, which are controlled by either electronic or vibrational processes in specific minerals. Electronic processes include the transition of an electron from one energy level to another within a metal ion, and charge transfer in which an electron passes from one ion to another. Vibrational processes include bending and stretching vibrations of bonds within radicals or molecules. In either process, photons with the specific energy to excite the process are absorbed so that light of the corresponding wavelength is not reflected. Vibrational processes cause absorption features that are relatively restricted in wavelength, but in electronic process the absorption spectrum is usually broader. The lattice environment of the atoms concerned modifies the wavelength of these absorptions. Thus, the absorption spectrum due to the presence of different minerals may vary by one or two hundred nanometers (Rothery, 1987). Iron is the only mineral responsible for strong absorption in the visible and near infrared region and is independent of the surface weathering (Hunt, 1970; Hunt, 1971;Hunt, 1974; Hunt, 1979 and Blom, 1980). Ferrous ion produces an electronic transition band near 1.0-1.1 µm when it is in clinopyroxene or amphibole and near 0.9-

1.1 µm when in olivine or orthopyroxene. In the case of hydrated iron oxide such as limonite, commonly produced by weathering, there is an absorption band at shorter wavelengths of about 0.55 µm. This gives rise to the visible red color, characteristic of iron staining. The absorption of ferric ion at 0.9 µm region may also be significant. The other significant absorption bands may be found in weathered clays near 2.2 µm. Carbonate minerals display a series of progressive absorption features from 1.6-2.5 µm due to internal vibration of the CO3 radical and vibrations of the whole radical within the lattice (Hunt, 1971). Table 5-2 shows some of the reflectance spectra for selected minerals expected in ophiolites.

Band selection For geological interpretations of arid regions, some authors suggest that a false color combination of bands 7,5,2 in red green and blue gives best discrimination between argilic and ferruginous alteration (Loughlin, 1985). Others, however, favor that ratios between the bands be used when selecting for mapping alteration zones (Abrams, 1983; Abrams, 1977; Podwysocki, 1983). Most authors do agree on the use of bands 7 and 5 with another band combination (Abrams, 1985). The choice of color in which to display each band depends on its information content and the way in which the human visual system perceives color information. In practice, when using interactive image processing systems it is usually best to make this decision by eye. Table 4-2 lists the 7, 5, 4 RGB band combination colors that can be used to distinguish different minerals and rock types (Rothery, 1987).

Image Enhancement The Landsat 5 Thematic Mapper (TM) records seven bands of reflected electromagnetic waves as digital images for each 185 km by 170 km section of Earth's surface. Three bands are in the visible segment of the spectrum, three in the infrared, and one in the thermal. Image resolution is approximately 30 meters. For the purposes of this study various image enhancement techniques were employed in order to increase the contrast between rock units. Materials that cover the Earth's surface have distinct spectral signatures for each spectral band. By combining a number of these spectral bands into one image, more information is represented in a single image and the result is a greater contrast between rock units. For each band, the percentage of the sun's energy that is reflected by each 28.5 meters by 30 meters area in a scene is recorded as a digital number (DN) between 0- 255 (Rothery, 1987). Through statistical "stretching" of a DN versus frequency histogram, the contrast between rock units is increased. Generally there are three techniques applied to TM images for enhancement consisting of spectral ratio, principal component and decorrelation stretch analyses. Each of these techniques is briefly described below.

Principal Component Analysis Principal component analysis (PCA) is an image enhancement technique for displaying the maximum spectral contrast from a number (n) of spectral bands with just

three primary display colors. Principal component analysis is commonly used to produce low dimensionality eigenvectors by which the dataset can be rotated (Davis, 1986). PCA has been utilized to estimate mineral components and abundance from reflectance spectra (Sasaki, 1983; Smith, 1985). PCA also resolves textural information. In this technique digital numbers (DN), assigned to pixels, are approximated to an ellipsoid in n- dimensional space, where n is the number of input bands. The first principal component is the direction in this space parallel to the longest axis of the ellipsoid. Therefore the first principal component contains the largest variance of the dataset. The successive principal components are orthogonal to the first through the next longest axis. The number of bands recorded by the satellite limits the number of principal components that can be created. For example three input bands can yield three principal components, where seven input bands can yield seven principal components. This enhancement effectively increases the contrast between the bands. One can choose which PC to view depending on the purpose of the study and nature of the study area. The PCA statistical treatment does not remove the atmospheric or environmental components of the DN. The enhancement does provide spectrally unique characteristics for each lithology. PCA is more useful for geological mapping in combination with spectral ratio analyses (Robinson, 1998). Advantages to using PCA are that data from all spectral bands can be displayed in three colors. In addition, principal component imaging can produce improved spectral contrast between spectrally unique terrain elements and the surrounding terrain and hence can be utilized for mapping. Disadvantages in using PCA are that the technique is scene dependent and is not robust, and the display colors in a PCA image may represent different materials in different images (Vincent, 1997).

Decorrelation Stretching Decorrelation stretching greatly improves the range of saturation, while the hue is not significantly distorted. The resulting image allows simple visual discrimination of color differences, or rock units. The essence of decorrelation stretching is shown by the cross-plots in Fig. 4-1. In Fig. 4-1a, the linear relationship between infrared bands 4 and 7, shows that similar spectral information is repeated in each band. Figure 4-1b shows that, after the data has been decorrelated, the images use a wider range of DN, providing excellent contrast between units. One advantage in using decorrelation stretching is that the technique is more robust and keeps the colors more nearly the same for a given target in images collected on different dates. In addition, it processes results in a more contrast- rich image than a spectral ratio image (Vincent, 1997). Potential problems with decorrelation stretching are that it mixes brightness (or temperature) with compositional information to a greater extent than spectral ratio images, and the results are not easily relatable to laboratory or field spectra (Vincent, 1997).

Display Color Reason Minerals Blue Low in 5 + 7 Clay (OH), Serpentine (OH) Cyan Low in 7 Clay (OH), CO3 Green Low in 4 + 7 Limonite (Fe, OH) Yellow Low in 4 Limonite (Fe, OH), Fe++ Red Low in 4 + 5 Fe++ Magenta Low in 5 No strong absorption

Table 4-2: Colors shown by rocks in a TM Landsat band 7, 5, 4 in RGB (after Rothery, 1987).

Figure 4-1: Cross plot of DN values; a) before stretching; b) after stretching (Rothery, 1987).

Spectral Ratios A spectral ratio (SR) is the division of one spectral band by another spectral band (Vincent, 1971). This process eliminates the atmospheric backscatter and the environmental portions of the digital number and lets one view the composition components of the reflectance directly. The spectral ratio method is based on the concepts that although spectral radiance is very sensitive to small changes in temperature band ratios are not (Watson, 1990). The SR method emphasizes composition because the atmospheric backscatter and the environmental components for a particular pixel are the same in every wavelength therefore and are eliminated. In contrast the specular and volume rays are absorbed preferentially at different wavelengths. Therefore SR values reveal compositional variations in the image. The ratio technique is particularly useful when compared with laboratory spectra (Vincent, 1997). The accuracy of the spectral ratio values depends on the combined accuracies of the radiance measurements and the temperature estimates. However, radiance and temperature can be detected to an accuracy of 0.07 to 0.3 %, respectively allowing a high degree of confidence in the processed results. Moreover the method is computationally more robust than PCA. Although the SR method is computationally more robust than PCA, it requires sophisticated registration algorithms and extremely careful spatial filtering to minimize signal to noise ratio (Hummer-Miller, 1990; Gillespie, 1986). In addition, atmospheric effects are also more complex to deal with in ratio data (Vincent, 1997).

Data Processing The Landsat-5 TM data processing method, used in this study, is described briefly here. Landsat TM data were purchased on CD-ROM in USGS NLAPS format. The data were downloaded from CD-ROM to the hard disks of personal computers. The header files were opened directly in ENVI 3.1 through the file menu option. In ERMapper 6.0, the header files were imported from the NLAPS format to the ERMapper format. The built in software functions were used to create band combinations, spectral ratios (3/4, 5/4, 7/5 in RGB) and principal components (from the PC 123 in RGB) for decorrelation stretching of the image. The results from both software packages were compared and the best selected for interpretation. Spectral signatures of different material were recognized by the combination of ground truth and existing ratio codes (Vincent, 1997; Robertson, 1998). The ERMapper 6.0 mosaic wizard was used to make a mosaic of the four scenes and the mosaic was exported as a file in a compressed mode to save disk space. The exported files were then imported into Arcview after downloading the ERMapper plug in for Arcview. All the processed image scenes were imported directly as raster layers and used as backdrops in Arcview. In this way three types of input layers could be opened in the GIS program: analytical data layers, digitized previous map layers and satellite image raster layers. The next step was to process the input layers to extract geological information for the area, and to determine the extent of individual lithologic units. With the help of previous

geological map layer themes, polygons for each distinct stratigraphic formation were constructed. The spatial extents of these polygons were then compared with image and analytical data themes. Any significant contacts between these three theme types were documented in a separate layer. Thematic tables were then constructed for each polygon that was contained relevant geological attributes. After the construction of polygons for each stratigraphic formation exposed in the area, these polygons were merged together with the geoprocessing extension of Arcview. The merged theme was classified as Geology Theme.

INTEGRATION MODEL

The final step in constructing the GIS for the study area consisted of combining the various maps to determine inconsistencies in the previously published maps. Processed satellite image theme layers, pre-existing map layers, event theme layers of analytical data and structural theme layers were combined together to resolve inconsistencies. These themes were integrated using information from all of the above themes to generate a new geologic map through a combination of data management, data visualization and thematic layering.

Data Management GIS proved to be a very efficient method for integrating remote sensing, map, field data, and laboratory data. The remote sensing data consisted of four processed satellite images. These images were mosaic and imported into Arcview as raster layers. Similarly, the scanned previous geological maps of the area were rectified according to the coordinate system of the satellite images. The following previous geological maps were included in the previous map view: the Kohat Quadrangle map by Meissner et al. (1975); the Bannu and Dera Ismail Khan Quadrangle map by Hemphill and Kidwai (1975); the Parachinar Quadrangle map by Meissner et al. (1974); the Colombo Plan map (Hunting Survey Corporation, 1961); the Amoco 1992 map (AMOCO Pakistan Exploration Company, 1970); the Gnos (1997) map; and the Robinson (1998) map. Biostratigraphically analyzed data were stored in an ACCESS database, created for this study, for display as overlays within Arcview. The database was designed in such a manner that each set of analytical components represents as an individual attribute. For example, for each sample longitude and latitude, a value was assigned so that analytical values could be overlaid on the satellite images and the previous map layers. This type of representation is generally known as polygon-based model. The polygon-based model stores the coordinates of those points that define the precise boundaries of mapped objects. Objects were represented as points (e.g. sample location), lines built up from multiple points (e.g. seismic lines, faults and fold axis), and polygons built up from multiple lines (e.g. lithologic units).

Data Visualization After construction of event themes from the spatial data it was possible to overlay and visualize the data. Based on the biostratigraphic and remote sensing data, presenting lithostratigraphic units were merged or extended or new units classified (Fig. 4-2). The processed images helped determine the spatial extent of these units. Polygons for each unit were constructed and saved as shape files. These polygons were associated with tables that contain spatial and related attribute information. Data for each point and polygon can be visualized by performing queries in the Arcview (Fig. 5-2).

Thematic Layering

Thematic layering entails separating spatial information by theme (e.g. lithology and structural geology). In the present study, multiple themes were developed to recognize several lithostratigraphic units exposed in the area. These themes include previous map themes, remote sensing themes, biostratigraphic themes and a new map theme.

Previous Map Themes Meissner Kohat Map theme Meissner et al., (1975), compiled the stratigraphy of the Kohat Quadrangle and created a geological map of the area. This map covers the Kohat Quadrangle and shows lithologies and contacts. However, due to highly deformed strata and lack of biostratigraphic age information, the distribution and contacts between stratigraphic units was grossly oversimplified.

Meissner Parachinar Map theme The Parachinar Quadrangle map was also compiled by USGS under the authorship of Meissner et al. in 1975. This map is similar to the Kohat Quadrangle map and provides considerable information on the lithostratigraphic units of the area.

Hemphill & Kidwai Bannu Map theme Hemphill and Kidwai (1973) compiled the stratigraphy of the Bannu Quadrangle, displaying lithologies and contacts. Due to lack of precise information regarding the chronological and regional extents of the lithological units, they could not differentiate between Cretaceous and Jurassic units.

Amoco Map theme AMOCO Pakistan (1992) prepared a map that covers Kohat and Partially Bannu area. This map gives considerable structural detail on the area.

Rock Type Color TM Bands Minerals 4B 5G 7R

Lava Magenta M L M Magneite Dykes Dark red L L M Mixture Sheeted dykes Dark orange L M M Fe++ (chlorite, epidote) Serpentine Purple L M Serpentine M Late Pink H-M M-L H Low in Fe and OH Intrusives Gabbro Orange-yellow M H M Limonite (Fe, OH), Fe++ Peridotite Dark purple L-M L L Serpentine, mafic minerals Felsic Gabbro Yellow L H Limonite, haematite H

Table 4-3: Colors of Decorrelation stretched TM images (after Rothery, 1988).

Colombo Plan Map theme

The old Colombo Plan map (Hunting Survey Corporation, 1961) depicts the distribution of different lithologic units. However, there is no information on ophiolites know to exist in the map area.

Menssier Map theme Mennessier (1977) compiled a map of Afghanistan that covers the northwestern corner of the study area and helps in distinguishing different types of mafic rocks in the region.

Gnos Map theme

Gnos (1997) compiled a map based on field and satellite data. This maps shows details on the ophiolites present in the area and regional tectonic framework.

Robinson Map theme

Robinson (1998, 2000), constructed a map outlining the distribution and structure of Waziristan ophiolites and adjacent rock strata through the use of satellite image.

Remote Sensing Themes

Band Combination theme The combination of TM bands 7, 5, 4 (Fig. 4-3) as a theme provided good spectral signatures of shale and limestone lithologies in the study area (Rothery, 1987).

Ratio theme The ratio image theme used for the study was 3/4, 5/4, 7/5 in RGB (Fig. 4-4). This theme was initially created to enhance the contrast between compositional differences among the igneous rocks in the Waziristan ophiolites (Robinson, 1998) but was extended over a much larger area as part of the present study.

Principal Component Analysis theme PCA theme used in this study was of the first three principal components of TM bands 4, 5 and 7 (Fig. 4-5). This theme is helpful in distinguishing between the ophiolites and sedimentary strata associated with ophiolites (Robinson, 1998).

Figure 4-2: Data visualizing in ArcView, the data associated with particular point or polygon theme can be seen by clicking on the view.

Decorrelation theme

The decorrelation stretching (Fig. 4-6) theme is extremely beneficial in determining the regional extents of the ophiolites and lithological boundaries within the in limestone rocks of the study area (Rothery, 1987).

Biostratigraphic Analysis Themes

Theme Contents Fig. 4-7 shows the attributes of the biostratigraphically-analyzed data. Each sample in the dataset is assigned by its appropriate geographic coordinate. Using X- coordinate as longitude and Y-coordinate as latitude, the data were brought into ArcView as an event theme and the data displayed as a point theme. The data for each sample contains the sample location, the precise biostratigraphic age assignment, and interpreted depositional environment.

Limitations

The study area is remote and mostly inaccessible, therefore field sample collection was restricted to the limited areas. There was very little previous GIS work done on this part of the earth and very little GIS data were available for the region, therefore the study heavily relied on remote sensing data.

NEW MAP CONSTRUCTION The primary objective of the GIS modeling was to improve the previous geological maps of the area in terms of age refinement and geographic extent of stratigraphic units. Figure 4-8 represents the new map containing stratigraphic layers derived from the previous maps compiled by Meissner et al., 1975, Hemphill and Kidwai, 1973; Mennessier, 1977; Colombo Plan and AMOC Pakistan, 1992. These layers were combined with the micropaleontological data of the area presented in chapter 2 and chapter 3. Figure 4-8 represents the new map layer based on biostratigraphic analysis integrated with remote sensing data. This layer elaborates the stratigraphic units according to their age and paleoenvironment assignment. Since the knowledge of depositional history of sediments is essential for the tectonic interpretation of any region, this thematic layer will help to interpret the tectonic history of the region. Combining the layer created from the previous maps and the layer created from our integrated data, a new map (Fig.4-8) was constructed.

Figure 4-3: Band combination of 7,5,4 in RGB to differentiate between shale and units. limestone

Figure 4-4: Ratio Image of 3/4, 5/4, 7/5 in RGB to differentiate limestone, and and limestone, 3/4, 5/4, 7/5 in RGB to differentiate of Image Ratio 4-4: Figure lithologies. opiolite

This integrated map shows the information about the regional extents of lithostratigraphic units, paleoenvironment, structural information, the exposure of ophiolites in the whole region and the contact between pelagic sediments and the ophiolites.

Statistical Comparison with Previous Maps In order to determine the changes between previous maps (Fig. 5-7 to 5-9) of the area and new map produced via GIS integration (Fig. 5- 7 to 5-10), a statistical comparison between the two maps was made. The layout of previous maps and new map with exactly the same scale were exported into two separate bitmap files. The bitmap files were open into MAP FACTORY, a raster based GIS software package as two separate layers. These two layers were then merged into a single layer and with the help of a built-in software function and a comparison between different colors assigned to different lithologic units was made. The areal extent of detected changes was then calculated in terms of square km. Table (4-4) shows the results of the calculated changes for particular lithologic units. From the table it can be deduced that there is a significant change in the area, which was defined as Triassic-Tertiary in the previous maps. Because of the biostratigraphic data incorporated into GIS model, this could be divided into individual time periods and epochs such as Triassic, Jurassic, Cretaceous and Eocene. Similarly the ages assigned as Mesozoic to Tertiary were subdivided into smaller time units such as Jurassic and Cretaceous. Cretaceous-aged rocks were also subdivided, into Early, Middle and Late Cretaceous on the basis of the biostratigraphic analysis.

Figure 4-5: First three principal components of TM bands 4, 5 and 7 in RGB to distinguish sedimentary strata and ophiolites.

Figure 4-6: Decorrelation stretch image of 7, 5, 4 band in RGB. This is helpful in determining the ophiolite spatial boundaries and distinguishing different types of limestone (Rothery, 1987).

Figure 4-7: Biostratigraphic data attributes, Sample No., Location, Formation, Lithology, Age and Paleoenvironment visualized in ArcView

Figure 4-8: Map constructed from previously existing maps of the area, which placed in view as backdrop and polygons of each lithological units were constructed.

Table 4-4: Statistical comparison of area changed from previous maps to the new GIS based map.

Figure 4-9: Map constructed from the previous map themes for statistical comparison with new map, significant changes occurred in the Triassic-tertiary undifferentiated and Mesozoic-Tertiary undifferentiated areas.

Figure 4-10: New GIS based map showing lithostratigraphy, biostratigraphy and paleoenvironment of the region.

CONCLUSIONS Geographic Information System (GIS) modeling has provided a platform for the integration of biostratigraphic and lithostratigraphic analytical and field data with remote sensing data. In the remote sensing data, Landsat Thematic Mapper (TM) data were utilized to create band combination, ratio images, principal component analysis and decorrelation stretch images. These processed images used in distinguishing various sedimentary and ophiolitic units in the study area as well as their regional boundaries. These images were incorporated as a backdrop layer in the GIS platform. Previously constructed geological maps covering smaller parts of the study area were successfully combined together in the GIS to make one map of the region. This map was used as previous map theme in the model. With the help of the satellite image and previous map themes, analytical and field data were incorporated to produce a new map of the northwest Pakistan. This map shows lithological boundaries using of the stratigraphic nomenclature defined by the stratigraphic committee of Pakistan, the age and depositional environment of each lithostratigraphic unit, and prominent structural features of the region. Statistical comparison of new and previous map shows a significant area change in units previously assigned as Triassic to Tertiary.

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