Tectonics of Pakistan - Engineering Geology - Lecture Slides, Slides for Genetic Engineering. Anna University of Technology
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Tectonics of Pakistan - Engineering Geology - Lecture Slides, Slides for Genetic Engineering. Anna University of Technology

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These are the Lecture Slides of Engineering Geology which includes Well Logging, Logging Units, Work Flow Chart, Lithological Boundaries, Inter-Borehole Correlation, Dip Determination, Fracture Frequency, Investigation ...
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Tectonics Of Pakistan

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INTRODUCTION

• Tectonics of Pakistan is characterized by two active convergent boundaries:

• In the northeast there is an active continent-island arc- continent collision boundary, the west end of the Himalayan origin.

• In the southwest, there is an active boundary of oceanic lithosphere subducting beneath arc-trench gap sediments and continental sediments the oceanic part of the Arabian plate passing under the Makran arc-trench gap and afghan microplate.

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TECTONIC SETTING

• The uplift of the main Himalayan Ranges is attributed to the buoyancy of the doubled Sialic crust over the mantle material and imbricate stacking of the Indian crust during collision.

• During the later stages of collision the upper crust of the Indo-Pakistani Plate became delaminated and transported south, carrying passive margin sequences in its hanging wall.

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TECTONIC SETTING

• On the leading edge of Indian Plate the foreland fold and thrust belts have been developed from north to south on the Indian plate itself and constitute the Himalayan collision zone in the north west of Pakistan.

• These belts are active and are known as: • Kashmir Mountains • Salt Ranges • Trans Indus Ranges • Sulaiman Range • Kirthar Range

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TECTONIC SETTING

• On the southern margin of the Himalayan Collision Zone the Kohat and Potwar Plateaus, Salt Range and Trans Indus Ranges were formed by the underthrusting of the Indian Plate beneath its own Phanerozoic sedimentary strata

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TECTONIC SETTING

• The Indian Shield is present in this part of world as a fragment of Gondwanaland.

• This shield is bounded by the Chaman, Ornach-Nal fault in the west.

• It extends, at least, up to the Indus Ophiolitic Belt underneath Himalayas in the north east.

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STRUCTURAL SETUP

Axial Belt This region lies along

the north-western border of Pakistan, against the microcontinental block of Afghanistan, and along the eastern side of the Ornach Nal/Chamman fault zone.

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STRUCTURAL SETUP

Punjab Foredeep, Central and Lower Indus Basins • This structural province covers most of the

central, southern and eastern parts of Pakistan. • It is bounded by the outcrop of the shallow

basement of the Indian Shield to the southeast and by the edge of the Mesozoic and Tertiary fold and thrust belt to the west.

• The Punjab Platform and eastern margins of the Central and Lower Indus Basins represent the gently north-westerly dipping leading edge of the Indo-Pakistan craton.

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Northern Montane Area

• Four regional fault systems that are Main Karakorum Thrust (MKT), Main Mantle Thrust (MMT), Main Boundary Thrust (MBT) and Trans-Indus Ranges Thrust has further subdivided the Northern Montane Area into five lithotectonic domains.

• These are characterized by distinctive stratigraphy and physiography.

• From north to south these geological belts are Karakorum Block, Kohistan Island Arc, Northern deformed Fold-Thrust Belt, Southern deformed Fold- Thrust Belt and Punjab Fore deep

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Karakorum Block

• The Karakorum block consists of complex assemblages of heavily deformed sedimentary, metasedimentary and igneous rocks of the southern Asian plate.

• It lies between Pamirs in the north and Kohistan– Ladakh Arc in the south.

• The collision between the Karakorum block and the Kohistan-Ladakh arc occurred along MKT in the Cretaceous time

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Main Karakorum Thrust (MKT)

• The Main Karakorum Thrust (MKT) is a major tectonic feature in northern Pakistan.

• This has been formed as a result of collision between the Karakoram plate in the north and Kohistan island arc in the south

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Kohistan Island Arc (KIA)

• The Kohistan Island Arc (KIA) developed in response to northward-directed subduction of Neo-Tethys underneath Asia during late Jurassic to Cretaceous time.

• In the NW Himalaya, collision between continental India and the KIA is interpreted as having occurred at between 50~55 Ma.

• The KIA represents a 40 km thick pile of mafic, ultamafic and calc-alkaline plutonic and volcanic rocks and has been widely accepted as a vertical section through an intraoceanic island arc.

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Main Mantle Thrust (MMT)

• The MMT marks the northern boundary of the northern deformed fold and thrust belt.

• Obduction of the Kohistan Island Arc occurred along the Main Mantle Thrust (MMT) with major uplift occurring between 30-15 Ma.

• The MMT dips northwards between 25-45 ̊ and is the southernmost thrust involving lower crust.

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Northern Deformed Fold & Thrust

Belt • The northern deformed fold and thrust belt

lies south of Main Mantle Thrust and is about 300 km wide.

• This belt comprises of heavily deformed sedimentary, meta-sedimentary and igneous rocks.

• This belt stretches from Kurram area in the west near Afghan border up to the Kashmir basin in the east.

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Main Boundary Thrust (MBT)

• The Main Boundary Thrust (MBT) represents the southwards migration of Himalayan deformation from the site of MMT.

• From northeast to southwest, it extends along the front of the northern fold and thrust belt around Hazara-Kashmir Syntaxes.

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TECTONIC EVOLUTION

• The Pakistani basins have acquired their primary structural and stratigraphic features from events associated with plate movements that occurred latest Paleozoic to the present.

• The Indo-Pakistani Plate has evolved through successive stages of plate tectonic events which are documented for the Eo-Cambrian onwards.

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SEDIMENTARY BASINS

• Following is the classification of Indus Basin:

• Upper Indus Basin: • Kohat sub-Basin • Potwar sub-Basin

• Lower Indus Basin: • Central Indus Basin • Southern Indus Basin

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UPPER INDUS BASIN

• This basin is located in the northern Pakistan and is separated from the Lower Indus Basin by Sargodha High.

• The northern and eastern boundaries coincide with the Main Boundary Thrust (MBT)-the southern most of the major Himalayan thrusts.

• The MBT runs through the Margala Hills, Kala Chitta and Kohat Ranges.

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UPPER INDUS BASIN

• The basin is further subdivided into: • Potwar, to the east • Kohat, to the west, by river Indus.

In the Kohat sub-Basin, west of the Potwar sub-Basin,

Eocene through Siwaliks strata are involved in a complex fold and thrust belt in which Eocene Salt occupies the cores of many of the anticlines. Moreover, Paleocene and Eocene stratigraphy is more

complete in Kohat sub-Basin.

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UPPER INDUS BASIN

Potwar Plateau is bounded on two sides by thrusts and two sides by strike slip faults.

• Northern and southern boundaries of Potwar

plateau are marked by MBT and SRT respectively.

• Eastern and western boundaries are marked by left lateral Jhelum Strike Slip Fault (JF) and right lateral Kalabagh Fault (KBF). Docsity.com

LOWER INDUS BASIN (SOUTHERN AND CENTRAL INDUS BASINS)

• Different classification schemes have been given to this basin by various experts.

Central Indus Basin: a. Punjab Platform b. Sulaiman Depression East Sulaiman Depression Zindapir Inner Folded Zone Mari Bugti Inner Folded Zone c. Sulaiman Fold Belt

Southern Indus Basin: a. Thar Platform b. Karachi Trough c. Kirthar Foredeep d. Kirthar Fold Belt e. Offshore Indus

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LOWER INDUS BASIN (SOUTHERN AND CENTRAL INDUS BASINS)

• The Central and Southern Indus basins are separated by Jacobabad and Mari-Kandhkot highs together termed as the Sukkur Rift.

• The Highs have been active since Jurassic times and at least up to Paleocene.

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CENTRAL INDUS BASIN • The basin is separated from Upper Indus Basin by the

Sargodha High and Pezu uplift in the north.

• It is bounded by Indian Shield in the east, marginal zone of Indian Plate in the west, and Sukkur Rift in the south.

• The oldest rocks exposed in this basin are of Triassic age (Wulgai Formation) while the oldest rocks penetrated through drilling are of Precambrian Salt Range Formation on Punjab Platform.

• The depth to the basement is about 15,ooo meters in the trough areas. Docsity.com

CENTRAL INDUS BASIN

• The basin comprises, from east to west, three main units on the basis of the topography of Indian Shield and later development, as follows:

a. Punjab Platform b. Sulaiman Depression c. Sulaiman Fold Belt

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PUNJAB PLATFORM • This unit marks the eastern segment of Central Indus Basin and

shows no surface outcrops of sedimentary rocks.

• Tectonically, it is a broad monocline dipping gently towards the Sulaiman Depression.

• The Pre-Cretaceous non-orogenic movements tilted the area

eastward during the Paleozoic and westward since Mesozoic resulting from the collision of Indian and Eurasian plates.

• Punjab Platform is tectonically the least affected area because of its greater distance from collision zone. However, this presents larger stratigraphic variations; Cambrian and Permo-Carboniferous strata appear to onlap against the Sargodha High.

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