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Title of Thesis  
SEDIMENTOLOGY AND PETROLOGY OF THE VOLCANICLASTIC ROCKS OF THE BIBAI FORMATION, ZIARAT DISTRICT, BALOCHISTAN, PAKISTAN  
Author(s)  
ABDUL TAWAB KHAN  
Institute/University/Department Details  
University of Balochistan, Quetta / Philosophy  
Status (Published/ Not Published/ In Press etc)  
Published  
Date of Publishing  
December, 1998  
Subject  
Mineralogy  
Number of Pages  
179  
   
Keywords (Extracted from title, table of contents and abstract of thesis)  
Sedimentology, Petrology, Volcaniclastic Rocks, Bibai Formation, Ziarat District, Geology, Sulaiman Fold Belt, Muslimbagh, Sulaiman, Thrust-Fold Belt, Quetta, Breccia, Sandstone, Mudstone, Ash beds, Lava, Volcanic Conglomerate (VC), Volcanic Breccia (VB), Sandstone interbedded with mudstone, (SSMS), Limestone (LS), Lava flows (VOL), Paleocurrent pattern, Lithofacies Distribution, Bibai Submarine,  

 

 
Abstract  

The Upper Cretaceous Bibai Fornlation is exposed in Kach-Ziarat and Spera Ragha-Chinjun valleys and near Muslimbagh, within the western part of the Sulaiman Thrust-Fold Belt east of the Quetta Syntaxis. The formation generally comprises basic volcanic rocks, volcanic conglomerate and breccia, sandstone, mudstone and ash beds. Within the Kach-Ziarat valley it is dominantly composed of volcaniclastic sediments and rarely lava flows, while, within the Spera Ragha-Chinjun valley dominantly the in-situ basaltic volcanic rocks. The volcaniclastic succession may be categorized into various facies viz volcanic conglomerate (VC), volcanic breccia (VB), sandstone (SS), sandstone interbedded with mudstone (SSMS), mudstone (MS), limestone (LS) and lava flows (VOL), which are comparable with the facies classes A, B, C, D, E, and F of Mutti & Ricci Lucchi (1972, 1975) and Pickring et al. (1986a), indicating deposition by sediment gravity flows and slumping / soft sediment deformation. The volcanic conglomerate, VCP-VCC-SS association of the facies, their stacking pattern, erosive bases and fining-upward trend suggest deposition within a channelized complex anastomosing on a submarine fan system. The SSMS facies of sandstone interbedded with mudstone, characterized by Bouma (1962) Tabcde, Tbcde, Tcde and Tde sequences, sole marks, soft sediment deformation, pinch-and-swell and general thinning- and fining-upward trends of 2nd-order cycles, indicate deposition by turbidity currents in over bank (-levee) complex between channels. The mudstone (MS) facies, possessing occasional thin sandstone beds in lower part and profusion of shallow marine fauna in upper part, indicate deposition in lower fan / basin plane conditions and shows an overall shallowing-up of the succession. Limestone (LS) facies, interbedded with volcaniclastic facies in lower part of the formation, is very finely crystalline (bio-micritic) possessing micro-foraminifera of the globotruncana family suggest deposition during calm periods when volcanic activity had been suspended intermittently. The general south-southwestward flow of the paleocurrent pattern and litho- facies distribution in various studied sections suggest that source area was north of the Bibai Peak. Texture, composition and whole rock geochemistry of rock fragments of the volcanic conglomerate indicate that sediments were derived from a hotspot related volcanic terrain where detritus of the alkaline acidic igneous rocks was also available, from time to time, along with the major proportion of basic volcanic rocks, also of alkaline nature. Based on characters of various facies associations, their vertical and lateral organization, paleocurrent pattern and composition of detritus, we propose that the Bibai Formation comprises a special category of "channel (-levee) –over bank complex", we name it the Bibai Submarine Fan, which developed on the slope of a series of seamounts (hotspot volcanos). Lithofacies and their associations clearly define the mid-fan, over bank (-levee) and lower-fan / basin plane components of the submarine fan. Seamounts developed on sea floor of the northwestern margin of the Indo-Pakistan Plate, which later on emerged, and provided detritus to the Bibai Submarine Fan. We suggest that the present trend of paleocurrents, generally southward, has been rotated anticlockwise along with its north and northeastward drift and anticlockwise rotation of the Indo-Pakistan Plate towards Eurasia during the Upper Cretaceous and later periods till present time. Its restoration by clockwise rotation back to its Upper Cretaceous (71.4+t.3.4 My) position would give its original west-northwestward paleoslope at the northwestern margin of the Indo-Pakistan Plate.

 
   
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Sr.No Chapter Table of Contents
 
i 180.kbs
170.KB
1 1

INTRODUCTION

1
57.KB
2 2 REGIONAL GEOLOGY OF THE AREA 5
238.KB
3 3 SEDIMENTARY FACIES 24
1728.KB
4 4 PETROGRAPHY AND GEOCHEMISTRY 68
4018.KB
5 5 PALEOCURRENTS AND PROVENANCE 135
71.KB
6 6 DEPOSITIONAL MODEL AND PALEOGEOGRAPHY 143
247.KB
7 7 SUMMARY AND CONCLUSIONS 159
62.KB
8 8 REFERENCES 165
144.KB
9 9 APPENDICES 179
493.KB