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SEDIMENTOLOGY AND PETROLOGY OF THE VOLCANICLASTIC ROCKS OF THE BIBAI FORMATION, ZIARAT DISTRICT, BALOCHISTAN, PAKISTAN

Khan, Abdul Tawab (1998) SEDIMENTOLOGY AND PETROLOGY OF THE VOLCANICLASTIC ROCKS OF THE BIBAI FORMATION, ZIARAT DISTRICT, BALOCHISTAN, PAKISTAN. PhD thesis, University of Balochistan, Quetta.

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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) /textarea></div><div class="formfieldname">References</div><div class="formfieldhelp">You are strongly encouraged to paste in the reference list of your item into the box below. It may be used to link your item to those it cites and to those that cite it.</div><div id="inputfield_referencetext" class="formfieldinput"><textarea accept-charset="utf-8" wrap="virtual" name="referencetext" rows="3" cols="60">

Item Type:Thesis (PhD)
Uncontrolled Keywords: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,
Subjects:Physical Sciences (f) > Earth Sciences(f4) > Mineralogy(f4.5)
ID Code:165
Deposited By:Mr Ghulam Murtaza
Deposited On:29 Jun 2006
Last Modified:04 Oct 2007 21:00

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