New Pepeort

FIELD REPORT OF SONA PASS KARACHI

DJ SINDH GOVT. SCIENCE COLLEGE KARACHI BATCH (2011-2012)

GROUP MEMBERS:

USAMA ARFAT TALAL BIN JAWID ISRAR-UL-HAQ RIMSHA KALEEM UROOJ SOHAIL HAREEM ILYAS FARRUKH ALI MEMON TUBA ANUM NUZHAT SALEEM AB.RAUF ASAD-UR-REHMAN ALI ASGHAR SAJID ISLAM HAMAS MALIK GULNAZ AHMED IQRA MEHMOOD YAZDAN ZUHAD

SUBMITTED TO: SIR: ADIL FAZAL DAD

ACKNOWLEDGEMENT:

Associate Professor Sir Maroof Hussan guide about the

purpose of field & basic field tips and tell us about the

History & economical importance of that area.

Co-operative Lecturer Sir Adil tells us about different

Geological structure present in that area. He also help us in

finding the “Dip and Strike” of the different Rock beds by the

help of different instrument

Lecturer Sir Arsalan tells us about the climatic

condition as well as the Fossils presence in that area. He also

tells about the litho logy of the area.

Acknowledgment: A statement of gratitude for assistance in producing a work.

ABSTRACT:

The area under study lies on the southwestern corner of the Karachi Trough, between Kirthar and Pab Ranges. The exposed rocks in the area are Nai and Gaj Formations of Oligocene and Miocene ages respectively. However, Kirthar Formation of Eocene age is also exposed in the northwestern part. These

formations are continuously exposed from the western coast of Karachi to northern Sindh, forming a series of asymmetrical folds and anticlines plunging southwest. The anticline structures have been complicated by several faults (Hasnain et al., 1987).

These formations consist of shale’s, sandstones, and limestone with some weathered materials from older-surrounding rocks. The composition of these formations has great influence on the distribution of toxic elements in the soil, vegetation and water of the area.

The instruments used in Sona pass are Brounton Compass, Jacob staff, Abney Level, Geological Hammer, and Measuring tape. We use these instrument for determination of Dip, Strike and taking samples of the rock, fossils and measured the thickness of rock Beds .

INTRODUCTION:

A field trip was arranged by the of Dept.

of Geology “DJ SINDH GOVT. SCIENCE COLLEGE” to

the area of “SONA PASS” Karachi by the great efforts of

Sir Adil & our worthy Head of the department of Geology

Sir Maroof Hussan . The reason behind to select this

particular side for this field trip was understanding the

structure geology of that area i.e. Fold, Fault etc as this is

included in our course of Bsc (pass).

LOCATION:

The area understudy lies on the south-western corner

of the Karachi trough . This location is situated 649 km south

west (210’) of the approximate center of Pakistan & 59 km

from Karachi air port .According to the geological location

LATITUDE: 24.89’

LONGITITUDE: 66.8’

LITHOLOGY:

The exposed rocks in that area are of Oligocene &

Miocene age of rock. The rocks in the area are forming a

series of asymmetric fold anticline plunging to southwest.

Several rocks have complicated the anti clinical structures

forming several faults.

This formation consists of sandstone

& limestone with some weathered rock materials from older-

surrounding rocks. The composition of this formation has

great influence on the distribution of vegetation & water of

the area .The ingredients of waste water form various

industries element may have introduced different hazardous

element in these rocks.

GEOLOGICAL HISTORY OF SONA PASS:

As the name indicates “Sona pass’’ come

because there is a pass present in that area. In past a

geological structure ‘Fault’ was formed by the effect of

external forces. The Sona pass is of Nari and Guj formation

and Oligocene and Miocene age respectively. Lithology of the

area shows that there was shallow marine environment in the

past after some time uplifting and tilting take place which

gives birth to new structure .Also there are some evidence

shows there was a river in the past .Later on movement of

plate take place which help in forming a fault.

APPROACH:

The route, which we followed to reach Sona pass area, was

shortest among all the routes to reach there.

Starting from DJ SINDH GOVT. SCIENCE COLLEGE, we

went to sona pass area via “Tower, Gul Baie , Sher

Shah ,Musroor base

OBJECTIVE:

The objectives of our field to Sona pass were;

To study the fossils and plantation

of the area.

To study the application of

weathering & changes brought on rocks by Weathering of

that area.

To find dip & strike of different

rock beds.

Measuring of different traverse & getting sample of these

traverse.

PURPOSE OF STUDY:

The purpose of our field to this particular side or certain area

to recognize the geological structures of that area as well as to

get used of the geological instruments to find dip & strike of

different rock beds . The main purpose of the field was to create

& develop research, communication skill and team work spirit in

the students.

METHODLOGY:

The following method we apply in the field;

We use Brunton compass for measuring dip and strike

of different strata.

We use Jacob staff and measuring tape for measuring

the vertical thickness of the strata.

We use Geology Hammer for collecting and trimming

of fresh samples.

We use Magnifying glass for visualizing the texture,

grain size and their arrangement.

We use HCL for identification of carbonated rocks.

GEOLOGICAL INSTRUMENT:

The instrument we used in the field were

DRAWING BOARD :

We used drawing board to study the map location

of the as well as to locate our location in the map.

BASE MAP :

A base map which was provide to us from whom we

study the geological area, structures and Different features

present that area.

FIELD BOOK :

In field book, we note the information about the rocks and

structures that we study in the area provided to us by our

Teachers.

SAMPLING BAG :

In sampling we collect and keep fossils and samples,

we collect in the field.

JACOB STUFF :

Jacob stuff were also provided to us that were a

straight wooden rod like instrument of 7 feet length that helps

us to measure the actual thickness of strata. In field, we use

Jacob stuff to calculate the vertical thickness of the rocks beds.

MAGNEFING GLASS :

As name indicates, this is used magnify different

object we used magnifying glass for visualizing the texture,

grain size & the arrangements of rocks. We also use it to

observe the microfossils.

HCL :

We use dilute HCL in the filed to identify the

carbonated rocks. If the carbonate rocks present the bubbles

come up.

BRUNTON COMPASS :

The geologists usually use Brunton compass. The

main purpose for which we use Brunton compass was to find

the Dip & strike of different rocks.

Brunton compass is mainly consists of following units;

A COLINMETER used for measuring dip angle.

A COMPASS used to measure direction.

A BULL’S EYE LEVEL is used to level the instrument.

ABNEY LEVEL :

An Abney level is used as an instrument in

measuring degree &, topographic elevation. This is

consisting of a fixed slight tube, a movable spirit level that is

connected to a protector scale.

GEOLOGICAL HAMMER :

Geological hammer is used to spittle & break rocks. In

field, we used it to obtain a fresh surface of a rock also

fossil, in order to determine the composition, nature,

mineralogy, history, & field estimate of the rock strength.

GEOLOGY OF THE AREA: SONA PASS HILL SIDE :

This is formed under the marine condition due to uplifting. The elevation of limited extent rising above the surrounding land with local relief of less than 300m.

SONA PASS FAULT :

A Fault is present in that area that is

particularly known as Sona pass Fault. As we know that, a

fault is a planar fracture Discontinuity in a volume of

across which there has been significant displacement along

the fractures, which shows evidence of relative movement.

This fault was recognizing as transform Fault that is due to

the horizontal displacement of rock masses. This

displacement provided natural passes and has made

accessibility easy across the area of Sona, Lal Bakhar e.t.c

CAP MOUNT ANTICLINE :

In addition, there is a fold present in that areas particularly known as Cap mount anticlines.

PHYSIOGRAPHY:

Physiographic ally the area of study may be divided into the

following four zones:

Hub Valley Zone: This zone lies in the northwestern part of the mapped area, extending on either sides of Hub River up to Pab Range in the north and Pir Mangho Hills in the south. This valley is occupied by gravel. Derived from rocks of Jurassic to Miocene ages with

few intervening rock outcrops of Eocene and Oligocene ages, which are mostly covered by Aeolian sand deposits.

Piedmont and Sub-Piedmont Zone: This area is extended From Pir Mangho in the north and merges into the coastal zone in south. This Piedmont and Sub-Piedmont Plain /Penne-Plain or Congo-plain has been formed by the receding sea. Whole of this terrain is occupied by gravel and shingle. The general slope of this terrain is towards southwest. Two small rivers, Lyari and Malir, drain this area. Neither of these rivers is perennial. A structurally higher hill is located between Malir and Lyari rivers.

Coastal Zone: This zone lies in the south of the surveyed area, along the coast, extending from Got Arab in the west to Got Rehri ip the east. It consists of vegetated tidal mud liuls, beach sand, coastal dimes,, coastal terraces, rock arches, stacks, wave cut platforms, bars and spits. The altitude of this terrain ranges upto 15 meters above the main sea level. The coast is emergent type, off shore bars, beach barrier like Sand spit indicate coastal emergence in recent times. Sand spit and Manora Island are part of an offshore bar behind which a lagoon is formed. This

lagoon serves as the Karachi harbor.

DRAINAGE: As explained in physiography, the area is drained, independently by Hub, Lyari and Malir Rivers having independent catchment's areas. Pir Mangho Hill Range acts as water-shed between Hub River and Lyari River. PECHS Hill is the watershed between Lyari River and Malir River. The drainage pattern in Hub valley is dendrite in mountainous areas and has a combination of dendritic and trellis pattern in the valley. In the south of Pir Mangho Hill Range the drainage pattern is a combination of trellises and dendritic pattern.

STRATIGRAPHY: The rocks exposed in the area are sedimentary from

origin and are laid down in shallow marine conditions. The sand stone in the lower Nari formation is classified as Ortho-Quartz & Quartz Argentites. The sand stone was deposited under in shallow marine environment with in the domain of the upper shelf associated with passive margin.The petrographic studies suggest mostly inter granular porosity, with very low amount of porosity. The porosity and permeability data indicates that the sand stone of lower Nari holds the potential to be hydrocarbon reservoir. They range in age from Eocene to Recent. Most of the area is occupied by the

rocks of Oligocene and Miocene ages. The rocks of Eocene age are exposed in the northwestern part of the study area (Shah, 1977). The formation which are found in the area are as given below.

NARI FORMATION : Nari formation is derived from Nari River In the Khither Range.Nari formation is of Oligocene age .Nari formation has been encountered in many offshore & on shore areas in and around Karachi. It is divided into Lower Nai member (Tobo member) and upper Nai member (Machani member). The member only found in sion pas Rea is described below.Lower Nari member (Tobo member ) Tobo members compose limestone in the lower part and sandstone and shale in the upper part. Limestone is brown, dark brown, hard, nodular, thin to medium bedded, fossiliferous and siliceous.

The upper part of Nari formation is well exposed. It consists of four distinct litho logical units and these units are mapped on litho logical distinction.

The shale is greenish-grey, grey, light brown white with rust on surface and weathers to orange- brown, rusty-brown, yellow brown, green, green-gray or khaki. Some surfaces are coated with hard

ferruginous black metallic oxide crust. Calcareous, hard, cross-bedded, ripple marked shale is brown khaki, yellowish - green, dark Reddish- brown, sot, blocky, earthy and sandy.

1. HALKANI SAND STONE UNIIT

Halkani sandstone unit is dark grey, brown, rusty brown, soft, medium bedded, medium to coarse grained inter- layered with shale which is light green, khaki, limonitic yellow, grey and sot. In the upper part the sandstone is coarse grained, gritty, calcareous, and hard.

GAJ FORMATION :

The Gaj Formation is from Miocene age of rock. Its period is tertiary and Era is Cenozoic. The contact b/w Nari and Guj formation is conformable. The Guj formation has been divided into Lower (Mol) and Upper (Sharji) members. Detailed description of Lower Gaj members is given below.

Lower member (Mol member):

The lower member (Mol) comprises of clay in the lower part and limestone in the upper part. The units are Metan clay unit is khaki, grey, grayish - brown

and brownish - khaki, sot to moderately hard and chunky, thin bedded, massive and fossiliferous, interrelated with thin beds of limestone.This is also sub-divided into three

1. METAN CLAY UNIT :

Metan clay unit is khaki, grey, grayish - brown and brownish -khaki, sot to moderately hard and chunky, thin bedded, massive and fossiliferous, interrelated with thin beds of limestone. On Hub Chowki road, it is 129 meters thick.

2.TALAWA LIMESTONE UNIT:

Talawa limestone unit is brown, golden-brown, weathers to rusty brown, grayish-brown, hard, thin to thick bedded, sandy limonitic, foraminifera and with fossil fragments less resistant than the underlain limestone. It erodes into blocks in Jhill hill area. It is 76 meters thick in Talawa area.

3. JHILL LIMESTONE UNIT:

Jhill limestone unit is very hard, thin-bedded, light brown to cream colored, massive and nodular. It is siliceous in some parts and fossiliferous, coralline, chalky in the weathered escarpment and resistant. It is 68 meter thick in Jhill hill. The thickness decreases in the east.

MOROHOLGICAL EEXPRESSION:

The lower member (Mol) of Gaj formation, which consists of clay in the lower part and limestone in the upper part, is more resistant than the underlying Nai formation and overlying upper Sharji member of Gaj formation. It forms prominent steeply dipping idges upto 221 meters high. The upper member of Gaj formation is less resistant and forms lower elevation than Nari formation.The upper member (Machani) of Nari formation is less resistant to weathering and the maximum elevation occupied by the most resistant limestone beds of Pir Mangho unit is 144 meters AMSL. The sandstone and sandy shale found interbedded with limestone are easily eroded and form a landscape of parallel tapeing low ridges. The sandstone in the upper part also forms edges but lower in elevation than the limestone of Pir Mangho unit. During the time of deposition of upper member of Nari Formation, the basin was being disturbed continuously. This is indicated by disruption in the supply of clastic sediments of Halkani unit followed by warm clear water condition favorable for biological growth.

ECONOMIC IMPORTANCE:

The sand stones horizons of lower Nari formation are classified

as Ortho-Quartz &Quartz Argentites.

There are some also kind of building stones are also found such

as lime stone which are used as building material .

The sand stone were deposit in a shallow marine environment

within the domain of upper shelf, associated with a passive margin.

The porosity and permeability data indicates that the sand stone

of lower Nari hold the potential to be hydrocarbon reservoir.

It is also recommended that the Indus off shore area should be-

evaluated with emphasis on Lower Nari to be studied as potential

horizon.

REFERENCES:

S.M Ibrahim Shah stratigraphy of Pakistan

Filed observation during field.

Previous data about Sona Pass feiled.

PAPG Annual Technical Confirence (2009)

www.searchanddiscover.com (WEBSITE)

SPE/PAPG ANNUAL TECHNICAL CONFERENCE 2009

November 17-18, 2009 Islamabad

“Reservoir Potential of Lower Nari Sandstones (Early

Oligocene) in “ Southern Indus Basin & Indus Offshore”

By Syed Amir Mahmood & Shamim Ahmed Sheikh

Introduction of formation Hsanain et al, 1987.

Stratigraphy Shah 1977.